A firm linked to the lawyer tasked by the prime minister with looking into the Greensill Capital lobbying scandal has been given £7m in government contracts over the last year.
Boris Johnson has asked top lawyer Nigel Boardman to lead an investigation into the now-collapsed finance firm's activities in government and the role its founder, Lex Greensill, played.
The Whitehall review will also examine how government contracts were secured by Greensill Capital, as well as the actions of former prime minister David Cameron.
The ex-PM approached serving ministers and officials about the involvement of Greensill Capital in government-backed financial support schemes during the coronavirus crisis, lobbying that included sending text messages to Chancellor Rishi Sunak.
Mr Cameron has said he broke "no codes of conduct and no government rules", but acknowledged: "As a former prime minister, I accept that communications with the government need to be done through only the most formal of channels, so there can be no room for misinterpretation."
When the investigation was announced, Mr Johnson's spokesman said the "independent review" would make sure the government is "completely transparent about such activities and that the public can see for themselves if good value was secured for taxpayers' money".
But Labour has raised questions about how independent the investigation will be.
Analysis by the party has found that 10 government contracts have been awarded to Slaughter and May, where Mr Boardman works as a consultant, totalling £7,229,989 since March 2020.
Mr Boardman served as a partner at the firm until 2019.
There is no suggestion of wrongdoing by Mr Boardman, but Labour's shadow Cabinet Office minister Rachel Reeves said government claims that the investigation will be independent are "lying in tatters" in light of the revelation.
"The more that emerges about this investigation, the more it looks like the Conservatives are set on glossing over cronyism in their ranks, so they can carry on like nothing has happened," she said.
"We need to put a stop to this cycle of cronyism. That is why Labour is calling for a full, transparent parliamentary inquiry into the Greensill scandal."
Sky News has approached both the Cabinet Office and Slaughter and May for a comment.