Boris Johnson has not tried to influence the Sue Gray report, a minister has insisted, as he said a meeting between the pair could have been about levelling up.
Nadhim Zahawi, the Education Secretary, sought to defend the Prime Minister over an alleged secret meeting he attended with Ms Gray, who is overseeing the report into the 'partygate' scandal.
It has been claimed that the pair met at least once during the time the report was being drafted, although a Whitehall source said its contents were not discussed at any point.
Mr Johnson's allies on Sunday night accused Ms Gray of "playing politics" and strenuously denied that the Prime Minister had attempted to "nobble" her inquiry.
Senior Tories told The Daily Mail that they were alarmed by "toxic" leaks from Ms Gray's team and the suggestion that she was "surprised" he received only one fine.
"Sue Gray is supposed to be neutral but she's been busy playing politics and enjoying the limelight a little too much," a source told the paper.
Mr Zahawi sought to downplay the talks on Sunday and the suggestion that they were held in "secret".
"She’s also the senior civil servant responsible for levelling up and making sure the United Kingdom gains the benefit in all its formations," he told the BBC’s Sunday Morning.
"The Prime Minister meets his civil servants all the time."
Mr Zahawi insisted he did not know who had called the meeting and that he did not believe any meeting was "material to the outcome of the investigation".
"Sue Gray is professional, and has the highest level of integrity," he added. "She is independent, the Prime Minister will never intervene, interfere, in the investigation."
The BBC initially reported that the discussions touched on whether photos would be revealed to the public, and that Ms Gray initiated the meeting "to clarify her intentions" for what would happen once the police investigation concluded.
However, a spokesman for the inquiry disputed this account of events, while a No 10 source insisted the request for the meeting did not come from Mr Johnson.
It has also been reported that the meeting was suggested by a No 10 official, while the calendar invitation was sent by Ms Gray.
It comes as about 30 people, including Mr Johnson, are being contacted by the Cabinet Office to warn them of the contents of the document ahead of its expected publication next week.
Most of the letters are believed to have been sent out on Thursday, as the Metropolitan Police concluded its investigation into lockdown breaches in Downing Street and across Whitehall.
Angela Rayner, Labour's deputy leader, has called on the Prime Minister to "urgently explain" why the "secret meeting" with Ms Gray took place.
Downing Street insisted that Mr Johnson had been "clear throughout" that the report should be "completely independent".
Speaking to LBC on Sunday, Anne-Marie Trevelyan, the International Trade Secretary, defended Ms Gray as "clear-headed" and "independent-minded".
Like Mr Zahawi, she said she did not know who had organised the meeting with Mr Johnson, adding: "I don't follow anybody's diaries."
Asked whether the details of who organised the meeting should be made public, she said: "I'm not sure that it makes any difference to me.
"I don't think Sue is in any way likely to be someone who's pushed around.
"She's an amazing, very clear-headed, strong and independent-minded lady, and she will publish the report she feels is right, as the Prime Minister asked her to do originally."
Pat McFadden, Labour's shadow Treasury minister, said he had "every faith" in the senior civil servant's integrity.
He told Sky News: "We don't know the details of that meeting, it's not clear who called it, there's different accounts of that, so it's hard for me to say what was said there.
"I do have faith in her integrity and let's see what she says when the report comes out."