Nobody warned me that it was against the rules," the prime minister said, adding: "I would have remembered that."

Former aide Dominic Cummings says he warned Mr Johnson at the time, and has accused him of misleading MPs about it.

Asked if he would resign if he was found to have misled MPs, Mr Johnson said: "Let's see what the report says."

Senior civil servant Sue Gray is due to publish a report into alleged Covid rule breaking at lockdown get-togethers in Downing Street and government departments.

PM was warned about lockdown drinks - Cummings

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Mr Johnson also made a public apology to the Queen over No 10 parties on the eve of the Duke of Edinburgh's funeral in April last year.

Appearing to be distressed as he was quizzed about the parties, he said: "I deeply and bitterly regret that that happened.

"I can only renew my apologies both to Her Majesty and to the country for misjudgements that were made, and for which I take full responsibility."

On Friday, Downing Street apologised to Buckingham Palace over the two staff parties - which were not attended by Mr Johnson - on 16 April, 2021.

The following day, the Queen sat alone - socially distanced from her family - as she mourned her husband.

'End of the road'

In his blog, Dominic Cummings, who was still working in Downing Street at the time of the drinks party on 20 May 2020, claimed the PM had waved aside his warnings.

Mr Cummings said the idea that a senior aide - the PM's Principal Private Secretary Martin Reynolds - would not have checked with Mr Johnson, after he was warned his invitation to drinks in the Number 10 garden broke the rules, "is not credible".

Two other former Downing Street officials told the BBC they remembered Mr Cummings telling them on that day he had advised the prime minister not to allow the drinks to go ahead.

Asked about Mr Cummings' claims on a visit to a North London hospital, Mr Johnson said: "I can tell you categorically that nobody said that this was something that was against the rules, that was in breach of the Covid rules."

Responding to his latest statement, Labour's deputy leader Angela Rayner said: "Boris Johnson clearly knows it's the end of the road.

"He's the prime minister, he set the rules, he didn't need anyone to tell him that the party he attended broke them.

"If he had any respect for the British public, he would do the decent thing and resign."

Lib Dem leader Sir Ed Davey said the prime minister was "just making it worse for himself" with his "empty excuses" and "transparent lies".

The SNP's deputy Westminster leader Kirsten Oswald said it was "clear the prime minister was not being frank" about events in the Downing Street garden. (BBC)

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