Boris Johnson is facing fresh questions over allegations he lied to a probe into his lavish flat revamp as speculation mounts his standards chief could quit.
Downing Street is in contact with Lord Geidt, who advises the PM on ministerial interests, after differing accounts emerged over the funding of the redecoration of the Downing Street flat.
Lord Geidt is reportedly on the brink of quitting over allegations he was misled by Mr Johnson during his investigation earlier this year.
The Prime Minister's official spokesman said Lord Geidt remained in post and added: "We are liaising with Lord Geidt to any answer further questions he may have."
The row began when the Conservative Party was fined £17,800 by the elections watchdog on Thursday, after it said the party had failed to correctly declare donations worth £52,800 from a firm owned by Tory peer Lord Brownlow.
The report found the Prime Minister had WhatsApped the peer in October 2020 to ask for more funds towards to luxury makeover of the flat he shares with his family.
The finding conflicts with Mr Johnson's claim to Lord Geidt that he wasn't aware of the source of funding for the flat until February 2021.
In May, Lord Geidt ruled that the PM had "unwisely" allowed the works to go ahead without thinking about who would foot the bill but he had not broken the ministerial code.
He will consider his position if Mr Johnson fails to explain why he did not share crucial evidence with him earlier this year, the Telegraph reported.
Lord Geidt's departure would be a major blow to the PM, whose previous standards adviser also resigned amid scandal.
Sir Alex Allan quit last November after Mr Johnson ignored his report which found Home Secretary Priti Patel had broken the ministerial code by bullying staff.
Labour 's Deputy Labour leader Angela Rayner has written to Lord Geidt calling for him to look into the differing accounts.
She said: "We now know that in the days before he imposed the 2021 winter lockdown, the Prime Minister went from allegedly hosting an illegal party in Downing Street to asking super-rich Tory donors to secretly fund the luxury refurb of his flat.
"Not only has the Conservative Party broken the law, but its Prime Minister has made a mockery of the standards we expect.
"If Boris Johnson refuses a fresh investigation, that standard will be lowered significantly - setting the bar woefully low for our country's public life."
However the only person who can launch investigations is the Prime Minister, according to Cabinet Office guidance.
Separately, Labour has also asked the Parliamentary Commissioner of Standards Kathryn Stone to investigate.
The Prime Minister's official spokesman denied Mr Johnson had lied, insisting he has "acted in accordance with the rules at all times".
In its defence, Downing Street said the Prime Minister did not know Lord Brownlow was providing the money to the "blind trust" he was organising.
A Conservative Party spokesperson said: "The Conservative Party has received notification from the Electoral Commission that, in their judgement, the manner in which a payment was reported represented a technical breach of reporting requirements under the Political Parties, Elections and Referendums Act.
"We have been in constant contact with the Electoral Commission with regards to this matter and have sought their advice as to how the transaction should be reported since it was made.
"We are considering whether to appeal this decision and will make a decision within 28 working days."
Separately, the Information Commissioner's Office said it had received a complaint relating to a Cabinet Office response to a freedom of information request about the renovation of the flat.
Downing Street was asked on Friday why the Electoral Commission had access to WhatsApp messages when an FOI request asking for them was unsuccessful.
The PM's spokesman said that the FOI request rules "were followed".
Q&A
Why is Boris Johnson in trouble over the revamp of his Downing Street flat?
Prime Ministers get an annual grant of £30,000 towards the upkeep of their home in No 10.
Boris Johnson and his wife Carrie exceeded this cap and reportedly spent as much as £150,000 on the makeover.
Some of the bill was picked up by the Cabinet Office on
the condition it would be reimbursed by the Tories.
So who did pay for the refurbishment?
Much of the bill was picked up by Tory peer Lord Brownlow through his firm Huntswood Associates.
The peer, who chaired the Downing Street Trust, gave £52,801 to the Tory Party to cover the cost of the work in October 2020.
The next month, after being contacted by the PM, he paid a further £59,747 to the suppler bringing the total cost of the refurbishment to £112,549.
After coming under pressure in the media and Parliament, the Prime Minister eventually paid the bill himself but it is not known how he covered the expense.
Why have the Tories been fined?
The Electoral Commission fined the Tories £17,800 for breaching electoral law. It said the party failed to declare the £52,801 from Lord Brownlow.
Tory chiefs tried to claim the sum was “not a donation to the party” but was “a donation to the PM via the party” or “a “gift to the nation”.
But the watchdog dismissed these claims, saying the full amount “was a donation and should have been reported to the Commission”.
Why is the Prime Minister in hot water?
Mr Johnson told his independent adviser on standards Lord Geidt he did not know the source of the flat funding until February.
The peer cleared him of breaking the ministerial code but said the PM had acted “unwisely” by not finding out who had footed the bill.
But the Electoral Commission report reveals Mr Johnson had sent a WhatsApp message to Lord Brownlow in October 2020 asking for more cash for “further, at that stage unspecified, refurbishment works on the residence”.
Following this exchange Lord Brownlow gave the additional £59,747. This suggests Mr Johnson misled his own ethics adviser.
Downing Street insisted that the Prime Minister had acted in accordance with the rules at all times.
