A limited version of the Cabinet Office inquiry by Ms Gray has been made public, a document which is likely to prove pivotal in determining prime minister's future as he faces anger over the partygate scandal.

Updates and reaction as version of Gray report is released - politics live

Addressing MPs in the Commons, Mr Johnson said: "I want to say sorry - and I'm sorry for the things we simply didn't get right and also sorry for the way this matter has been handled.

"It's no use saying this or that was within the rules and it's no use saying people were working hard. This pandemic was hard for everyone."

Labour leader Sir Keir Starmer said: "There can be no doubt that the prime minister himself is now subject to criminal investigation.

"The prime minister must keep his promise to publish Sue Gray's report in full when it is available, but it is already clear what the report disclosed is the most damning conclusion possible."

Key points in the version of the Gray report include:

• Some of the behaviour surrounding these gatherings is difficult to justify

• A number of the gatherings should not have been allowed to take place or to develop in the way that they did

• At least some gatherings represent a serious failure to observe not just the high standards expected of government but also of the standards expected of the entire population

• There were failures of leadership and judgment by different parts of No 10 and the Cabinet Office

• The garden at 10 Downing Street was also used for gatherings without clear authorisation or oversight. This was not appropriate.

• Some staff wanted to raise concerns about behaviours they witnessed at work but at times felt unable to do so

Gray says Met probe means she can't provide 'meaningful report' at this stage

Last week, the Metropolitan Police launched a criminal investigation into potential breaches of COVID regulations in Downing Street and Whitehall and requested Ms Gray's report make only "minimal reference" to events it is looking at.

Sixteen events in 2020 and 2021 were investigated as part of her inquiry.

Her update reveals there are only four events the Metropolitan Police will not be investigating as part of its separate inquiry.

The 12 gatherings being looked into by the Met include an event that happened at the Downing Street flat on 13 November 2020, the night aides Dominic Cummings and Lee Cain left their Number 10 roles, and an event to mark the PM's birthday on 19 June 2020.

Ms Gray said the police investigation means it is "not possible at present to provide a meaningful report" setting out all she has discovered.

"As a result of the Metropolitan Police's investigations, and so as not to prejudice the police investigative process, they have told me that it would only be appropriate to make minimal reference to the gatherings on the dates they are investigating," her update states.

"Unfortunately, this necessarily means that I am extremely limited in what I can say about those events and it is not possible at present to provide a meaningful report setting out and analysing the extensive factual information I have been able to gather."

Ms Gray said she has opted not to publish factual accounts of events not under investigation by police because to do so would damage her overall findings.

PM sets out response to Gray report

Mr Johnson told MPs he was making changes to the way Downing Street and the Cabinet Office are run "so that we can get on with the job that I was elected to do and the job that this government was elected to do".

"First it is time to sort out what Sue Gray rightly calls the fragmented and complicated leadership structures of Downing Street which she says have not evolved sufficiently to meet the demands of the expansion of Number 10 and we will do that, including by creating an Office of the prime minister with a permanent secretary to lead Number 10," he said.

Finishing his statement, the PM said: "I get it, and I will fix it. I want to say to the people of this country I know what the issue is."

He added: "It is whether this government can be trusted to deliver, and I say 'yes we can be trusted to deliver'."

Tory MPs decide if they are supporting PM or not

The PM has come under pressure to resign over the partygate revelations concerning gatherings in Downing Street and across Whitehall during COVID restrictions in 2020 and 2021.

Some of his backbenchers have already called for Mr Johnson to go, while a number of others have said they were waiting for the release of the Gray report before deciding whether to send a letter to the 1922 Committee of Tory MPs demanding a contest.

Former minister and vice-chair of the Conservative Party Andrew Mitchell said the PM no longer has his backing after the release of the inquiry's pared-back findings.

Tory MP Tobias Ellwood said if Mr Johnson fails to publish the Sue Gray report in full "he will no longer have my support".

And former PM Theresa May said the report demonstrates that Number 10 "was not observing the regulations they had imposed on members of the public".

She said this means her successor "had not read the rules or didn't understand what they meant and others around him, or they didn't think the rules applied to Number 10".

Mr Johnson replied: "No, Mr Speaker that is not what the Gray report says, I suggest that she waits to see the conclusion of the inquiry."

Opposition MPs call for Mr Johnson to go

Labour deputy leader Angela Rayner said the findings of Ms Gray's pared-back report are "sickening".

She told Sky News that Mr Johnson has "lost of the confidence of the British public" and should resign.

In the Commons, she asked the PM if he was at the No 10 flat gathering on 13 November, but he said he would "not indulge in running commentary" and she will have to wait for the Met investigation.

Lib Dem leader Sir Ed Davey called on Conservative MPs to do their "patriotic duty" and get rid of Mr Johnson.

"He must go before he does our country any more harm," he said.

Ian Blackford, the SNP's Westminster leader, said Mr Johnson's position was "completely untenable".

"The prime minister is guilty of breaking lockdown rules and misleading parliament. He must resign - or be removed from office," he said.

Mr Blackford accused the PM of lying to the Commons, for which he was ousted by the Speaker and was seen being escorted out by security.