Speaking to Kay Burley, Liz Truss said the government would release the "findings" from the Cabinet Office inquiry, which is being led by senior civil servant Sue Gray.

There have been calls for Number 10 to release the document in full.

PM braces for release of 'partygate' report - politics live

'Security issues' with publishing report

However, the foreign secretary said there could be "security issues" which mean parts of it are "problematic to publish".

"But we will absolutely publish the findings of the report," she pledged.

Ms Truss also said Boris Johnson has her "100% support" as the prime minister faces calls, including from some of his Conservative MPs, to resign over the partygate revelations.

The foreign secretary said she did not attend any parties in Downing Street and was not invited to any.

The crisis engulfing the PM deepened on Tuesday when the Metropolitan Police announced it is investigating a "number of events" in Downing Street and across Whitehall for potential breaches of COVID-19 regulations.

Read more: What could Sue Gray's inquiry into No10 parties mean for PM and who decides what happens next?

Uncertainty over report's publication

Expectations had been raised that Mr Johnson would address the Gray report's findings in the Commons this lunchtime.

On Tuesday afternoon, it was understood that Number 10 would publish the report compiled around midday today and then the PM would make a statement in the Commons after PMQs.

But it is now believed the document will not be released for publication until later this afternoon at the earliest, with the chances of this being delayed until Thursday growing.

Uncertainty has been cast over its publication as Ms Gray's team hold discussions with the Metropolitan Police.

Calls for full investigation to be made public

Opposition parties had voiced concern on Tuesday that, if published today, they would not be given sufficient time to read the document before any potential statement from the PM later in the day.

Sky News understands Ms Gray wants the report to be published in full and it will cover all the alleged events, not just those the police are not investigating.

Labour has called for the report to be published "in full" - with leader Sir Keir Starmer saying anything less would amount to a "cover-up".

The party's shadow education secretary Bridget Phillipson said the revelations had turned the UK into an "international laughing stock" and accused ministers of devising "ridiculous excuses".

"I think it's now for senior Conservative politicians, for the Conservative Party, to think whether they really want to continue to put the country through this. It's time the prime minister just did the decent thing and resigned," she said.

Met Police launch criminal investigation

Metropolitan Police Commissioner Dame Cressida Dick announced the force was investigating "a number of events" for potential breaches of COVID-19 regulations.

Mr Johnson told the Commons yesterday he welcomed the probe and said it would "help draw a line under matters".

The force has written to the Cabinet Office, formally requesting it refers all relevant information from its inquiry to help support the investigation. Sources have told Sky News this investigation will take "weeks, not days".

Downing Street has said the PM is willing to be interviewed by police but does not believe he has broken the law.

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Photos of No 10 parties show PM next to wine bottles

Legal commentator Joshua Rozenberg told Sky News that if Mr Johnson were to be interviewed under caution he would "clearly be a suspect" as he is suspected of committing a criminal offence.

Mr Johnson's leadership has come under severe pressure amid the ongoing partygate scandal and he could face a vote of no confidence if more than 54 Conservative MPs submit letters of no confidence to the 1922 Committee of backbench MPs.

Opposition parties and some critics on his own backbenches say any evidence he has misled parliament would amount to a breach of the ministerial code and require the prime minister's resignation.

Yesterday evening, it was understood that Ms Gray had received photographs showing Mr Johnson and others close together with wine bottles when COVID rules were in place as part of her investigation.