David Cameron has denied reports by the BBC he was paid £7.2 million by Greensill Capital before it collapsed and said he "acted in good faith at all times."
Greensill, which was founded by an Australian entrepreneur and lent money to businesses such as Liberty Steel, went into administration in March.
The BBC’s Panorama team claimed they had seen documents which suggested Mr Cameron cashed in Greensill shares in 2019 worth £3.25m.
The programme said the former prime minister had made a total of £7m before tax in the two and a half years that he worked for Greensill.
But a spokesman for Mr Cameron said claims were "attempting to define a role for David Cameron at Greensill that is totally at odds with the facts."
He said Mr Cameron "did not receive anything like the figures quoted by Panorama" and claimed the payments were a “private matter” for the former prime minister, who was in power from 2010 until he resigned shortly after the Brexit referendum in 2016.
Two years later, he became an adviser to Greensill, which was set up by Lex Greensill, and lobbied his former colleagues, including Chancellor Rishi Sunak.
Greensill lent £3.6 billion to the GFG Alliance, owned by Indian steel magnate Sanjeev Gupta, according to Panorama.
After Greensill went into administration, 5,000 UK jobs at Liberty Steel - part of the GFG Alliance - were put in jeopardy.
Earlier this year, Mr Cameron told the Treasury Committee his text-message lobbying of ministers and senior civil servants was driven by an "idea" to channel government funds to small businesses crippled by the coronavirus lockdown.
At one point he badgered Mr Sunak for a government-backed COVID emergency loan but Mr Cameron told the committee Greensill had not been looking for a “bailout”.
The Treasury Committee decided Mr Cameron had showed a "significant lack of judgement" in his relationship with Greensill but he was cleared of breaking the rules on lobbying.
In a statement released on Monday night, Mr Cameron's spokesperson said: "David Cameron deeply regrets that Greensill went into administration and is desperately sorry for those who have lost their jobs.”
"As he was neither a director of the company, nor involved in any lending decisions, he has no special insight into what ultimately happened,” the statement added.
It went on: "He acted in good faith at all times, and there was no wrongdoing in any of the actions he took. He made the representations he did to the UK government not just because he thought it would benefit the company, but because he sincerely believed there would be a material benefit for UK businesses at a challenging time. He had no idea until December 2020 that the company was in danger of failure.”