A Cabinet minister has denied that Boris Johnson is “sleazy”, following allegations the Prime Minister asked Conservative donors to secretly pay for Downing Street refurbishments.

Labour is expected to pile further pressure on the Government over claims made by Mr Johnson’s former aide, Dominic Cummings that the Prime Minister wanted donors to “secretly pay for the renovation” of his official flat, in a move called “unethical, foolish, possibly illegal” by the ex-Vote Leave campaigner.

Asked about the allegations, Defence Secretary Ben Wallace said Mr Johnson had paid “out of his own pocket” for the Downing Street upgrade.

Mr Wallace told BBC Radio 4’s Today programme: “Do I think the Prime Minister is sleazy? No, I don’t.

“Do I think the Prime Minister is an absolutely first-class leader who has led this country in a pandemic?

“Let’s not forget, while we are getting into Oscar-type gossip columns – there is an awful lot of gossip going around.

“He paid out of his own money to refurbish the flat. He paid for his flat.”

The Opposition will ask Commons Speaker Sir Lindsay Hoyle to grant an urgent question requiring a minister to come to the House to respond to the charge that Mr Johnson plotted for Tory donors to put up the money for the work.

Over the weekend, International Trade Secretary Liz Truss insisted the Conservative Party leader had complied fully with the rules and had paid for the refurbishment, which reportedly ran to £200,000, out of his own pocket.

But during a round of broadcast interviews, both Mr Wallace and Ms Truss repeatedly refused to say whether the bill was initially settled by the Tory Party, or one of its donors, in which case it should have been declared as a loan under party funding rules.

Labour’s Kate Green said there were “very troubling allegations” surrounding the work at the Number 11 flat, as her party called for the Electoral Commission, which has been looking into the matter, to start a full inquiry into how the changes were funded.

The shadow education secretary told the Today programme: “I’m glad they (the Electoral Commission) are looking into it because clearly these are very troubling allegations and they go to the heart of ethics and integrity in our Government, and transparency.

“It seems to me that as long as there is uncertainty, there is doubt and innuendo and rumour about who is getting contracts, who is paying for the refurbishment of the Downing Street flat, who is in and who is out.

“This is distracting the Government. They are not getting on with the right priorities for the country because they are busy fighting among themselves and seeking to throw up a smokescreen.”

In an apparent reference to the briefings battle with former de facto chief of staff Mr Cummings, Ms Green said the Government had been “fighting like rats in a sack”.

The Electoral Commission, which first raised the issue with the Conservatives more than a month ago, confirmed at the weekend it was still looking into whether any of the sums relating to the work on the flat should have been declared.

Last week, the Daily Mail published details of an email from Tory peer Lord Brownlow in which he said he was making a £58,000 donation to the party “to cover the payments the party has already made on behalf of the soon-to-be-formed ‘Downing Street Trust’”.

To date, no such trust has been formed.

Mr Wallace said: “The Prime Minister has complied at all stages with the rules and we’ve been very clear on that.

“We have engaged with the Electoral Commission and we will continue to engage with that.”