No.10 has denied that Boris Johnson lied about payments for the refurbishment of his Downing Street flat.
On Thursday the Conservative Party was fined £17,800 by the Electoral Commission.
The watchdog said the party had failed to properly report the donation from Tory peer Lord Brownlow which paid for the refurb.
The prime minister lives in a flat above No.11 Downing Street with his wife Carrie.
Lord Geidt, the ministerial standards adviser, said Johnson told him he knew nothing about the payments until immediately prior to media reports in February 2021.
But the Electoral Commission saw evidence that Johnson had sent Lord Brownlow a WhatsApp message in November 2020 “asking him to authorise further, at that stage unspecified, refurbishment works on the residence”, to which he agreed.
The prime minister’s spokesperson said while Johnson knew Lord Brownlow was the chair of the “blind trust” which was paying for the refurbishment, he did not know the money came from Lord Brownlow himself.
“He was not aware of the details of the underlying donor,” the spokesperson said.
“Lord Brownlow did not make a decision about becoming the person to cover the costs until after that exchange.
Asked if the prime minister lied to Lord Geidt and the public, the spokesperson added: “No.”
Deputy Labour leader Angela Rayner has called for Parliamentary Standards Commission Kathryn Stone to investigate Johnson over the donations.
It is the latest in a series of scandals that have hit the government, including the ongoing row over whether No.10 staff held a Christmas Party last year in breach of lockdown rules.