Dominic Raab has defended Boris Johnson as having been “crystal clear” about who footed the bill for his lavish Downing Street flat refurbishment.
The foreign secretary dismissed the allegations against the prime minister as “tittle-tattle” and "chatter" on Sky News' Sophy Ridge on Sunday.
But he also declined to deny a report in The Sunday Times that a second invoice for the flat renovations may have been settled by a Tory donor.
Scottish Tory leader Douglas Ross said on Sunday that Johnson must quit if he was found to have broken the ministerial code.
“I think people expect the highest standards of those in the highest office of the land and that’s why I think people are looking at the investigations that are currently ongoing and waiting for the answers,” he told the BBC’s Andrew Marr Show.
It comes after new claims emerged that an MP received a complaint from a Tory donor, saying they were asked to pay for a nanny for Johnson's one-year-old son Wilfred.
The donor was alleged to have said: "I don't mind paying for leaflets but I resent being asked to pay to literally wipe the prime minister's baby's bottom."
Asked about the allegation in The Sunday Times, Raab admitted he has “no idea” if a donor was asked to pay for Johnson’s childcare.
Watch: UK in 'last lap' of coronavirus fight, Dominic Raab tells Sky News
He said: "I have no idea, you don't have conversations like that with the PM. I can't comment on every little bit of gossip that's in the newspapers.
"The last thing you asked me about I think is an example of tittle-tattle."
Raab declined to deny another allegation that a second invoice for the renovations – reported to cost up to £200,000 – was settled by a third party directly with the supplier, saying: “I think the prime minister has been crystal clear about it.”
He added: "There are three reviews now I think into this and I think the right thing for me to do is not add political commentary that could otherwise prejudice those reviews but to respect the integrity of them.
"So I'm not going to offer you I'm afraid any more commentary or if you like chatter on the various different reports and speculation that I see in the Sunday papers."
Asked about new claims that Johnson personally called newspaper editors to criticise former aide Dominic Cummings, Raab also said he had "no idea".
It comes amid signs that the recent claims against the prime minister may be damaging the Tories.
Johnson is trying to refocus attention on tackling crime and the coronavirus recovery in a pitch to voters before polls open across Britain on Thursday.
Two new polls suggested the Conservatives' lead over Labour has been cut ahead of Thursday's local elections in England and votes for the parliaments in Scotland and Wales.
The polls will raise concerns among Conservatives that recent "sleaze" allegations battering the prime minister are beginning to turn some voters off.
The Electoral Commission this week launched an investigation into whether any donations or loans to pay for the refurbishment of his Downing Street flat were properly declared.
A No 10 spokeswoman said: "The prime minister has covered the cost of all childcare."
But she did not respond when asked if Johnson paid for the original bill himself or had reimbursed somebody else.
Johnson has denied breaking any laws over the refurbishment of his No. 11 residence and insisted he had paid "personally" for the works.
But he has refused to say whether he received an initial loan from the Conservative Party, as Downing Street launched two separate reviews into the controversy.
Questions intensified when Cummings accused the prime minister of wanting donors to "secretly pay" for the works in a "possibly illegal" move.
The elections on Thursday will be the first major electoral test for the Conservatives and Sir Keir Starmer's Labour Party since the 2019 general election.
Watch: Boris Johnson faces growing calls to explain how he funded Downing Street flat