Boris Johnson has hit out at "bizarre and unacceptable" new claims he broke COVID lockdown rules after being referred to the police by the Cabinet Office.
The former prime minister's ministerial diary has revealed visits by friends to Chequers during the pandemic.
The trips to the country residence were highlighted during preparations for a public inquiry into COVID, as well as new allegations about his behaviour in Downing Street, according to The Times which first reported on the story.
Mr Johnson complained of a "politically motivated stitch-up" after the information was passed onto the Metropolitan Police and Thames Valley Police, saying the events in question were "lawful".
Sky News understands all legal options are being considered by his team.
His spokesperson said: "The assertion by the Cabinet Office that there have been further COVID rule breaches is totally untrue.
"Lawyers have examined the events in question and advised that they were lawful.
"No contact was made with Mr Johnson before these incorrect allegations were made both to the police and to the privileges committee. This is both bizarre and unacceptable.
"For whatever political purpose, it is plain that a last-ditch attempt is being made to lengthen the privileges committee investigation as it was coming to a conclusion and to undermine Mr Johnson."
The privileges committee is investigating whether Mr Johnson misled parliament over his partygate denials.
The Cabinet Office said the information was passed on "in line with the civil service code".
But Mr Johnson's statement said: "The events in question were all within the rules either because they were held outdoors or came within another lawful exception. They include regular meetings with civil servants and advisers.
"It appears some within government have decided to make unfounded suggestions both to the police and to the privileges committee.
"Many will conclude that this has all the hallmarks of yet another politically motivated stitch-up."
Mr Johnson's lawyers have written to the police "to explain in detail why the Cabinet Office is entirely wrong in its assertions".
Police 'assessing' concerns
Police are currently "assessing" concerns, but a formal investigation has not yet been launched.
A statement from the Metropolitan Police said the details were passed to them on 19 May and they relate "to potential breaches of the Health Protection Regulations between June 2020 and May 2021 at Downing Street".
A Cabinet Office spokesperson said: "Information came to light during the process of preparing evidence for submission to the COVID Inquiry.
"It was identified as part of the normal disclosure review of potentially relevant documents being undertaken by the legal team for inquiry witnesses.
"In line with obligations in the Civil Service Code, this material has been passed to the relevant authorities and it is now a matter for them."
Johnson 'should consider his position as MP'
The Liberal Democrats have called for Mr Johnson to consider his position as an MP.
Deputy leader Daisy Cooper said: "It's outrageous that rumours of alleged rule breaking by Boris Johnson are still being drip-fed to the public.
"The fact that it's one rule for them and one rule for the rest of us still triggers a raw sense of injustice in millions of people.
"Sunak must make sure that not a single penny more of taxpayer money is spent on Johnson's legal fund, and Johnson should finally do one decent thing and consider his position as an MP."
Lindsay Jackson, spokeswoman for the Covid-19 Bereaved Families for Justice group, branded Mr Johnson "totally unfit for any form of public service" and suggested he "quietly step back from public life".
Labour called for the taxpayer-funded legal support for Mr Johnson, which is an estimated £222,000, to come to an end and said he had "serious questions to answer".
Deputy Labour leader Angela Rayner said: "The public will be shocked that they're still paying Boris Johnson's legal bills while he rakes in millions from speaking gigs, all because Rishi Sunak is too weak to put a stop to it.
"The Conservatives are now so preoccupied by their own scandals and haunted by their own failure that they are unable to tackle the problems facing the country. Only a Labour government can turn the page on 13 years of Tory sleaze."
'World has moved on from partygate'
However, allies of Mr Johnson have jumped to his defence.
Former cabinet minister Jacob Rees-Mogg said he went to Chequers with his children during the period being investigated by police and the visit was "entirely within the rules".
"The latest stories are just another example of how those who don't like Boris, mainly because of Brexit, are always looking for something to have a go at him on. It is a supreme non-story," he said on his GB News show.
Ben Bradley, the Tory MP for Mansfield, said the world "has moved on" from partygate, telling Sky News: "My sense of all of this is that, frankly, the former prime minister has been through that, we've investigated that, the country's dealt with that - I think the world's moved on."
The partygate scandal overshadowed the end of Boris Johnson's premiership and played a major role in his downfall last year.
Details of drunkenness, fighting and late-night parties at the heart of government while the nation lived under lockdown restrictions were laid bare in a damning report by Sue Gray - who said "senior leadership" must take responsibility for a culture of rule breaking.
Its publication came after the Met Police concluded its investigation into lockdown-breaking events in Downing Street and Whitehall, which resulted in 126 fines being issued for 83 people.
Mr Johnson received one of those fines, for attending his own birthday party in the cabinet room in Downing Street in June 2020.
He narrowly survived a confidence vote in June 2022 but was brought down a month later over his handling of the Chris Pincher affair.
The privileges committee is now investigating whether Mr Johnson knowingly misled parliament with his repeated insistence that rules were followed at all times.
He could be suspended from the Commons and face a by-election if they find he purposefully misled the House.