More than 1.1 million people will now be affected by tougher restrictions on home visits after they were extended to two more areas in the west of Scotland.
The measures will apply in Renfrewshire and East Dunbartonshire from midnight after a rise in positive cases.
The rules had already been reimposed in Glasgow city, West Dunbartonshire and East Renfrewshire last week.
First Minister Nicola Sturgeon said acting quickly now could "stem the tide of transmission" in the area.
People are being told not to host people from other households inside their own homes, or visit another person's home.
Meetings in pubs and restaurants and outdoor areas are still permitted - although the Scottish government said the hospitality sector would be monitored in the coming days to see whether restrictions should be extended.
A further 78 positive cases were reported in the Greater Glasgow and Clyde health board on Monday.
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Ms Sturgeon said it was "too early" to say whether the fresh lockdown had had any effect on cases.
The measures are targeted at household meetings, with Ms Sturgeon saying it was "still the view of public health teams that the significant factor driving transmission is people meeting up in their own homes".
She said local authorities in the area would "pay close attention to hospitality" and would encourage people to act responsibly while using bars and restaurants.
The widened restrictions - which also mean there should only be "essential" visits to people in hospitals and care homes - will be reviewed in a week's time.
Ms Sturgeon said the measures are not yet being extended to Lanarkshire or Inverclyde - noting that levels of infection were "significantly lower" in Inverclyde.
The restrictions will now apply to apply to 179,000 people living in Renfrewshire and 108,000 in East Dunbartonshire.
The city of Glasgow has a population of 633,120, while there are 95,530 people in East Renfrewshire and 88,930 in West Dunbartonshire.
Ms Sturgeon said it was "regrettable we are in this position", but that the measures banning household visits were "considered proportionate but also the most effective".
She added: "If we act quickly and preventatively now, we can stem the tide of transmission and avoid having other restrictions put in place."
The first minister had earlier warned that a continuing rise in Covid-19 cases in Scotland could see her government "put the brakes" on the planned easing of some restrictions.
An average of 152 positive tests have been recorded each day over the past week - compared to 14 per day six weeks ago.
The number of hospital admissions and deaths has not risen as sharply, although Ms Sturgeon warned that "this may just be a matter of time".
The man murdered during a spate of stabbings in Birmingham early on Sunday morning has been named as Jacob Billington.
In a statement, his family said: "Jacob was the light of our life and we have been devastated by his loss.
"He was a funny, caring and wonderful person who was loved by every single person he met.
"He lit up every room with his boundless energy and witty humour and the loss of such a special person will be felt by all who knew him for years to come."
Police said Mr Billington, 23, was stabbed in Irving Street at about 1.52am on Sunday while out with school friends from Liverpool - they were visiting one of their group who is studying in Birmingham.
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Image:Police yesterday released CCTV images of a man they wished to trace in connection with the attacks
Another friend, also 23, was seriously injured and remains in hospital in a critical condition.
A man was earlier arrested on suspicion of murder and attempted murder over the stabbings.
More from Birmingham
He was detained at a property in the Selly Oak area of the city at around 4am on Monday, said West Midlands Police.
The 27-year-old, who escaped the scene, is being questioned after a huge effort to track him down.
Image:The stabbings happened in the early hours of Sunday
Another man, aged 30 who was stabbed in Livery Street, and a 22-year-old woman, attacked in Hurst Street, also remain in a critical condition in hospital.
Four others were injured too.
Birmingham police commander, Chief Superintendent Steve Graham, said: "We are working hard to discover what led to the apparently random attacks.
"We have no suggestion that the motive was either racial, homophobic or gang-related."
He added: "Officers worked through yesterday and into the early hours of this morning in a bid to trace the man we believe responsible for these terrible crimes.
"We issued CCTV footage of the suspect and had a strong response from the public. I'd like to thank everyone who shared our appeal and who provided information to the investigation.
"One line of enquiry ultimately led us to an address in the Selly Oak area this morning where a man was arrested.
"Clearly this is a crucial development but our investigation continues."
The man murdered during a spate of stabbings in Birmingham early on Sunday morning has been named as Jacob Billington.
In a statement, his family said: "Jacob was the light of our life and we have been devastated by his loss.
"He was a funny, caring and wonderful person who was loved by every single person he met.
"He lit up every room with his boundless energy and witty humour and the loss of such a special person will be felt by all who knew him for years to come."
Police said Mr Billington, 23, was stabbed in Irving Street at about 1.52am on Sunday while out with school friends from Liverpool - they were visiting one of their group who is studying in Birmingham.
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Image:Police yesterday released CCTV images of a man they wished to trace in connection with the attacks
Another friend, also 23, was seriously injured and remains in hospital in a critical condition.
A man was earlier arrested on suspicion of murder and attempted murder over the stabbings.
More from Birmingham
He was detained at a property in the Selly Oak area of the city at around 4am on Monday, said West Midlands Police.
The 27-year-old, who escaped the scene, is being questioned after a huge effort to track him down.
Image:The stabbings happened in the early hours of Sunday
Another man, aged 30 who was stabbed in Livery Street, and a 22-year-old woman, attacked in Hurst Street, also remain in a critical condition in hospital.
Four others were injured too.
Birmingham police commander, Chief Superintendent Steve Graham, said: "We are working hard to discover what led to the apparently random attacks.
"We have no suggestion that the motive was either racial, homophobic or gang-related."
He added: "Officers worked through yesterday and into the early hours of this morning in a bid to trace the man we believe responsible for these terrible crimes.
"We issued CCTV footage of the suspect and had a strong response from the public. I'd like to thank everyone who shared our appeal and who provided information to the investigation.
"One line of enquiry ultimately led us to an address in the Selly Oak area this morning where a man was arrested.
"Clearly this is a crucial development but our investigation continues."
The government will introduce a new law that could change post-Brexit customs plans with the EU - but No 10 denied it would "tear up" the existing treaty.
The two sides agreed in 2019 on the terms of the UK's exit, including on future trade in Northern Ireland.
Reports suggested a new law could "override" the legal force of that deal - the withdrawal agreement.
But Downing Street said it would only make "minor clarifications in extremely specific areas".
No 10 confirmed the new UK Internal Market Bill will be published on Wednesday.
The EU said the "full implementation" of the withdrawal agreement was a "prerequisite for the negotiations on the future partnership" between the bloc and the UK.
The news comes at the start of another week of negotiations on that future trade deal.
The so-called transition period - which has been in place since the UK left the EU in January - will end on 31 December and the two sides are trying to secure an agreement to take its place.
But Boris Johnson said if a deal was not reached by the European Council meeting on 15 October, both sides should "move on" - meaning the UK would go on to trade with the bloc on international trading terms.
Labour's shadow Northern Ireland secretary, Louise Haigh, said if the government's latest moves were negotiating tactics, they were not "very effective".
She told BBC News: "It undermines all the progress that's been made over the last several months and completely jeopardises a future trading relationship."
What had the UK and EU agreed?
The two sides signed off on a withdrawal agreement last year ahead of the UK leaving the bloc on 31 January.
The document covered a number of areas, from how much the UK would have to pay for its "divorce bill" through to intentions for a future relationship.
But one of the biggest sticking points throughout negotiations had been how to handle the issue of Northern Ireland.
Both the UK and EU sides were committed to protecting the peace process in the region and preventing any reintroduction of border checks on the island of Ireland.
But they also accepted the land border between Ireland and Northern Ireland would become the UK's border with the EU, so customs rules needed to be respected and adhered to.
The UK and EU settled on the Northern Ireland Protocol.
This would see Northern Ireland continue to follow some EU customs rules after the transition period - meaning customs declarations would be needed for goods moving from Northern Ireland to Great Britain, as well as some new checks on goods going from Great Britain into Northern Ireland.
It was unpopular with some sections of the Tory backbenches and Northern Ireland's Democratic Unionist Party - which had been supporting the government until that point.
But the agreement was passed through Parliament and the Northern Ireland Protocol became part of the international treaty.
What is the UK government now proposing?
No 10 has said it is committed to the withdrawal agreement and the Northern Ireland Protocol.
And it said it was continuing its work with the EU in a joint committee to iron out issues around how the it would work in practice.
However, it said it wanted to have something in place to protect trade across the four nations of the UK if an agreement was not reached by the end of the year.
The text of the bill has yet to be published, so we cannot say for definite what will be included in its wording.
But Downing Street said one thing it would do is allow ministers to unilaterally decide what particular goods were "at risk" of entering the EU when passing between Great Britain and Northern Ireland, and therefore subject to EU tariffs.
The law would also give ministers the powers to scrap export declarations on goods moving from Northern Ireland to Great Britain and would make it clear that EU state aid requirements - where governments give financial support to homegrown businesses - would only apply in Northern Ireland.
But the government insists the bill only introduces "limited and reasonable steps" to "remove ambiguity" - not "overriding" the withdrawal agreement, as government sources had suggested on Sunday.
What has been the reaction?
There has been concern from Brussels over the messages coming out from Downing Street.
European Commission President Ursula von der Leyen tweeted that she trusted the UK government "to implement the Withdrawal Agreement, an obligation under international law and prerequisite for any future partnership".
And she added that the Northern Ireland Protocol was "essential to protect peace and stability on the island and integrity of the single market".
Northern Ireland's Deputy First Minister Michelle O'Neill tweeted any threat of backtracking on the protocol would be a "treacherous betrayal which would inflict irreversible harm on the all-Ireland economy and the Good Friday Agreement".
She has co-signed a joint letter from anti-Brexit parties in Northern Ireland to the prime minister and the EU's chief negotiator, Michel Barnier, saying it would be "entirely unacceptable [to] abandon these safeguards and mitigations".
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Labour accused the government of "misleading the public" over having a so-called "oven-ready deal" for Brexit.
Shadow health secretary Jon Ashworth told BBC Radio 4's Today programme: "Parliament supported the Withdrawal Agreement earlier on this year. He has made promises and signed a treaty around these arrangements for Northern Ireland, and he now seems to be backing out of that."
And Scottish First Minister Nicola Sturgeon said the move would "significantly increase" the likelihood of leaving the transition period without a trade deal, and the "resulting damage to the economy will be entirely Tory-inflicted. What charlatans".
But government sources told the BBC the legislation was "not intended to derail the talks", and a spokeswoman said the UK would continue to approach talks with the EU in good faith.
"As a responsible government, we are considering fallback options in the event this is not achieved, to ensure the communities of Northern Ireland are protected," she added.
A teenager has been arrested after a 15-year-old boy was seriously injured in a shooting as he made his way to school.
Police were called to the Grange Farm area of Kesgrave in Suffolk at around 8.40am on Monday to reports of a shooting.
Suffolk Constabulary said the victim suffered serious injuries and was airlifted to Addenbrooke's Hospital in Cambridge, where he is receiving urgent medical attention.
Image:An aerial view of the scene of the shooting in Kesgrave, Suffolk
The suspect, whose age has not been revealed, was arrested shortly before 11am in Ipswich - around five miles away from the scene - and is currently being questioned on suspicion of attempted murder.
Assistant Chief Constable Rob Jones said: "We believe this was an isolated incident and there is nothing now to suggest a wider threat to the public.
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"However, understandably, the community in Kesgrave, particularly in the Grange Farm area, will be extremely shocked and concerned. And furthermore, it's inevitable that parents across Ipswich will be anxious following this morning's incident.
"I'd like to reassure the public, that our priority is to keep everyone safe and that incidents like this are extremely rare in Suffolk.
"We've made an arrest as part of this investigation and we're currently working with all our partners and with the schools, to ensure that everyone feels safe when they're collecting their children from school this afternoon and in the days ahead.
"There'll be more police officers on patrol today, and we're going to be providing reassure in the area. I would ask anyone with information about this incident, to please come forward."
Image:Forensic officers are pictured at the shooting scene
Kesgrave High School had earlier confirmed one of its Year 11 students was involved in the incident.
"We have made aware by the police that there has been a serious incident involving one of our Year 11 students, on their way to school," the school said in a tweet.
"Students in school are safe and we are managing the situation in constant, close communication with the police.
Image:The suspect was arrested in Ipswich - five miles away from the shooting scene
"Students are to remain in school and will be kept safe in liaison with the police. Police will be present in the area and around the school throughout the school day.
"At the present time we are expecting students to be dismissed at the end of the school day, 3.20pm, as normal."
Image:A police officer is pictured outside the victim's school in Kesgrave
Nearby Friends Walk and Through Jollys have been completely closed off and there is a partial closure of Ropes, police said.
Members of the public are asked to avoid these area, which has been cordoned off by officers.
Any witnesses, or anyone with information about this incident, is asked to contact Suffolk Police on 101 quoting reference CAD 58 of 7 September.
