Boris Johnson has signalled he is willing to speak to police investigating multiple allegations of Downing Street parties breaching coronavirus rules, but believes he has not broken the law.

The Prime Minister said he welcomed Scotland Yard’s investigation and expressed hopes officers will “help to draw a line under matters” after his leadership was plunged into deeper jeopardy by the development on Tuesday.

The announcement also cast uncertainty over senior civil servant Sue Gray’s internal investigation into claims of lockdown breaches, which she was planning to publish this week.

Downing Street initially suggested that elements of the long-awaited Cabinet Office inquiry that touch on potentially criminal acts may be paused now police are involved.

But after it emerged Scotland Yard had not objected to any publication, No 10 insisted it was not trying to block the report and said Ms Gray’s team were in talks over “what may or may not be published”.

Commissioner Dame Cressida Dick said officers are investigating a “number of events” in Downing Street and Whitehall over two years, after being passed information from the Gray inquiry.

Updating the Commons on the inquiry, Mr Johnson said: “That process has quite properly involved sharing information continuously with the Metropolitan Police, so I welcome the Met’s decision to conduct its own investigation because I believe this will help to give the public the clarity it needs and help to draw a line under matters.”

The Prime Minister’s official spokesman said that “anyone asked to will co-operate fully” when asked if Mr Johnson is willing to be interviewed by officers.

Boris Johnson and Cressida Dick
Boris Johnson being steadied by Dame Cressida Dick as he observes a self-defence class during a visit to Metropolitan Police training college in Hendon, north London (Aaron Chown/PA)

Pressed if the Prime Minister thinks he has not broken the law, the spokesman said: “I need to be cautious about what I say but I think that’s fair to say that he does not.”

The spokesman initially said Ms Gray’s team “won’t publish anything that relates to the work of the police” under “standard practice” once an investigation begins, but can continue to work on allegations that do not reach the police’s “threshold”.

But the PA news agency understood Scotland Yard had not objected to the publication of any part of the Gray report.

Sources close to the investigation suggested that Ms Gray was considering her options and is concerned about publishing a report which was shorn of some of its key findings.

Downing Street updated its position in the afternoon, with the Prime Minister’s official spokesman saying: “There are discussions still ongoing between the investigations team and the police.

Prime Minister Boris Johnson
Prime Minister Boris Johnson jogging in central London (Aaron Chown/PA)

“That still needs to be worked through, both in relation to what may or may not be published and the ongoing work of both the police and the (Gray) investigation.”

Some Tory MPs have publicly called for Mr Johnson’s resignation, but others have said they will await the publication of the Gray report before trying to trigger a vote of no confidence.

The Cabinet Office has not set out how the latest development affects the publication of the report, with a spokesman saying that work is “continuing”.

Dame Cressida announced the investigation had opened at a meeting of the London Assembly’s Police and Crime Committee.

She said they are looking at “a number of events that took place at Downing Street and Whitehall in the last two years in relation to potential breaches of Covid-19 regulations”.

The investigation was opened as a result of information from the Gray inquiry and “my officers’ own assessment”, Dame Cressida added.

She pledged to only give updates at “significant points” and declined to say which alleged parties are under investigation, nor would she put a timeline on when officers could detail their findings.

“The fact that we are now investigating does not, of course, mean that fixed penalty notices will necessarily be issued in every instance and to every person involved,” she said.

Dame Cressida said investigations are carried out into “the most serious and flagrant type of breach” where individuals knew they were committing an offence or “ought to have known”.

She said “several other events” that appeared to have taken place in Downing Street and Whitehall had also been assessed, but they were not thought to have reached the threshold for criminal investigation.

Deputy Assistant Commissioner Jane Connors, the Met’s Covid-19 lead, will oversee the investigation being carried out by the special inquiry team, which works on sensitive and confidential work involving high-profile subjects and offences by those in public office.

Deputy Labour leader Angela Rayner questioned how Mr Johnson can remain Prime Minister with Downing Street under police investigation.

Boris and Carrie Johnson
Prime Minister Boris Johnson with his wife Carrie (Jacob King/PA)

“Boris Johnson is a national distraction. Conservative MPs should stop propping him up and he should finally do the decent thing and resign,” she added.

The Met had been under pressure to open an investigation for weeks, with the Daily Mirror first reporting allegations of parties in No 10 during Covid restrictions two months ago.

Fresh allegations have emerged at a steady pace since then and have now totalled at least 19 separate events.

The latest emerged on Monday when Downing Street was forced to admit Mr Johnson had a birthday celebration inside No 10 during the first lockdown.

Downing Street conceded staff “gathered briefly” in the Cabinet Room following a meeting, after it was alleged 30 people attended and shared cake despite social mixing indoors being banned.

ITV News reported the Prime Minister’s wife, Carrie Johnson, had organised the surprise get-together complete with a chorus of “happy birthday” on the afternoon of June 19 2020.

Interior designer Lulu Lytle admitted attending, but said she was only present “briefly” while waiting to talk to Mr Johnson about the refurbishments she was carrying out at the couple’s flat above No 11.

Chancellor Rishi Sunak was understood to have briefly attended as the gathering was breaking up, as he entered the room to attend a Covid strategy meeting.

ITV reported picnic food from M&S was eaten and Martin Reynolds, Mr Johnson’s under-fire principal private secretary, was also said to have attended, as was No 10’s director of communications Jack Doyle and head of operations Shelley Williams-Walker.

Social gatherings indoors were forbidden under lockdown laws at the time, with a relaxation of the regulations permitting gatherings of up to six people to take place outside.