Boris Johnson is facing questions over how expensive renovations at his Downing Street flat were paid for.
Labour has called for a full inquiry into the issue.
The prime minister and his fiancee Carrie Symonds carried out renovations on their home, the flat above 11 Downing Street.
There has been speculation the bill could be as much as £200,000, despite the fact the prime minister only receives an annual public grant of £30,000 to spend on the flat.
The issue was thrust into the spotlight on Friday after a blog post by his former chief adviser, Dominic Cummings.
Mr Cummings alleged Mr Johnson once planned to have donors “secretly pay” for the work on his flat. He said this was “unethical, foolish, possibly illegal and almost certainly broke the rules on proper disclosure of political donations if conducted in the way he intended”.
Labour wants the prime minister to reveal the full amount spent and who paid in the first place.
Painting, sanding and floorboard work had been done by longstanding Downing Street contractors, Cabinet Office Minister Lord True said.
“Any costs of wider refurbishment in this year have been met by the prime minister personally,” he added.
Details of how much of the £30,000 allowance was spent during the 2020-21 financial year are not yet available.
It is not clear whether any money originally came from another source – which the prime minister then paid back.
Asked whether he had ever discussed using donations to pay for refurbishments, Mr Johnson said: “If there’s anything to be said about that, any declaration to be made, that will of course be made in due course.”
There are questions over transparency.
Political parties have to report any donations or loans if they are above £7,500.
MPs must also declare – within 28 days – any donations which could influence their actions.
The government is supposed to publish a list of ministers’ financial interests twice a year. The last one was released in July 2020.
The Electoral Commission says it is trying to establish whether any funds relating to the renovations fall within the remit of political donations, and need to be published.
Labour leader Sir Keir Starmer urged a “full and transparent investigation”, arguing that the allegations risk undermining trust in government.
There have been reports Mr Johnson tried to set up a charitable trust to preserve Downing Street’s heritage (a scheme of this kind pays for restoration work at the White House).
According to a leaked email obtained by the Daily Mail, the Tory peer Lord Brownlow said last October he was making a donation to the Conservative party. He said this included “£58,000 to cover the payments the party has already made on behalf of the soon to be formed ‘Downing Street Trust’ – of which I have been made chairman”.
A second leaked email from Lord Brownlow in June 2020 showed the decision to set up the trust was taken by Mr Johnson as long as 10 months ago, the paper reported.
But to date, no such trust has been formed.
Lord True said the government had been looking at the question of funding Downing Street through a trust – an arrangement which he said would mirror those for other official government residences such as Chequers and Dorneywood.
Like several of his recent predecessors, Mr Johnson and Ms Symonds are living at No 11 because the four-bedroom flat there is much larger than the one above No 10.
Tony Blair was the first prime minister to live at No 11 – he and his wife Cherie turned the space into a family home for themselves and their three (later four) children.
The Grade 1-listed flat was then extensively refurbished by David and Samantha Cameron in 2011 at a cost of £30,000.
The latest upgrade for the flat was carried out by interior designer Lulu Lytle, a source has told the BBC.
The couple wanted to transform the flat from Mr Johnson’s predecessor Theresa May’s “John Lewis furniture nightmare” into a “high society haven”, according to the society magazine Tatler.