David Cameron has said he was paid "far more" as a part-time adviser to now-collapsed Greensill Capital than when he was prime minister.
He told MPs he had had a "big economic investment" in the finance company, including shares.
But he insisted he was not motivated by money when he lobbied ministers on behalf of the firm - and he believed he had acted in the national interest.
Mr Cameron was paid £150,402 a year when he quit as prime minister in 2016.
Speaking via video link to the Treasury Select Committee, he repeatedly declined to reveal his exact salary at Greensill, which he joined two years after leaving Downing Street, calling it a "private matter".
The panel of MPs is among three parliamentary committees that have launched inquiries into the company, following its collapse in March.
Mr Cameron told the Treasury Committee he had not broken any rules when he tried to influence ministers and officials on behalf of Greensill Capital around the start of the Covid pandemic in spring last year.
He said it had been "appropriate" for him to call and text ministers and officials directly, as financial schemes were being designed quickly at a "time of extraordinary crisis".
But he conceded that in future "prime ministers should only ever use letter or email, and should restrict themselves far more".
And he backed a tightening up of the rules for ministers and officials who take jobs in industry.
'Great regret'
Mr Cameron has previously said he began working as a "part-time senior adviser" to Greensill Capital in August 2018.
"I was paid an annual amount, a generous annual amount, far more than what I earned as prime minister, and I had shares - not share options but shares in the business - which vested over the period of time of my contract," he told the committee.
He described reports he had been set to make £60m from Greensill before its collapse as "completely absurd".
Mr Cameron also said the demise of Greensill Capital was a "great regret" to him, and there were "important lessons to be learned" from it.
He added that he had conducted "quite a lot of due diligence" before taking up the advisory role, including asking questions about "every aspect of the business".
- It's another word for trying to persuade the government to change its policies
- It can be done by individuals, companies, organisations and charities who contact ministers, backbench MPs and other politicians
- Some organisations and companies employ professional lobbyists to make their case for them
- Former MPs and civil servants often work as lobbyists
"I had a big economic investment in the future of Greensill, so I wanted the business to succeed," Mr Cameron told MPs. "I wanted it to grow."
He said his economic interest in the firm had been "important" but was not relevant to the MPs' inquiry into its collapse and its contacts with government.
And he said he had felt the firm's proposals would help small businesses access cash during an economic crisis, and were "absolutely in the public interest".
In a separate hearing, with the the Public Accounts Committee, Mr Cameron said he had only learned that Greensill Capital was in financial difficulty towards the end of last year.
He added that the past few months, during which his work for the company has come in for widespread criticism, had been "very difficult", but said he felt more sorry for the hundreds of staff who had lost their jobs.
The former prime minister repeatedly texted ministers and officials, including Chancellor Rishi Sunak, asking for the firm to be included in a Covid-related government loan scheme.
But his attempts to involve Greensill in the Covid Corporate Financing Facility were ultimately unsuccessful after they were rebuffed by the Treasury.
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2021-05-13 18:37:42Z
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