- Prime Minister's Questions
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Prime Minister Boris Johnson has apologised for attending a "bring your own booze" party during the first coronavirus lockdown.
He told MPs the event in the Downing Street garden was "technically within the rules" but he should have realised how it would look to the public.
Labour leader Sir Keir Starmer said the PM must now quit over what he called his "ridiculous" lies and excuses.
Mr Johnson is also under pressure from his own MPs over the May 2020 party.
The Commons fell silent at the start of Prime Minister's Questions, as Mr Johnson admitted he had been at the event for about 25 minutes, so that he could "thank groups of staff" for their hard work.
- Live: Johnson faces MPs at prime minister's questions
He added: "With hindsight I should have sent everyone back inside.
"I should have found some other way to thank them, and I should have recognised that – even if it could have been said technically to fall within the guidance – there would be millions and millions of people who simply would not see it that way."
He sat stony-faced as opposition MPs called for him to quit as prime minister, or for his own MPs to force him out. In all, the PM faced eight calls to stand down during the Commons question session.
Sir Keir Starmer said: "There we have it. After months of deceit and deception, the pathetic spectacle of a man who has run out of road.
"His defence…that he didn't realise he was at a party is so ridiculous that it's actually offensive to the British public.
"He's finally been forced to admit what everyone knew, that when the whole country was locked down he was hosting boozing parties in Downing Street. Is he now going to do the decent thing and resign?"
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Mr Johnson said he understood the "rage" of people who had "made huge sacrifices throughout this pandemic" at the thought "that people in Downing Street were not following those rules".
"I regret the way the event I have described was handled. I bitterly regret it. And wish that we could have done things differently."
But he urged MPs to wait for the outcome of an inquiry by senior civil servant Sue Gray into alleged Covid law-breaking in Downing Street, which he said "will report as soon as possible".
SNP Westminster leader Ian Blackford said that if Mr Johnson had "no sense of shame", then the Tory backbenchers "must act to remove him".
Liberal Democrat leader Sir Ed Davey also called on the PM to resign.
Tweeting after the Mr Johnson's statement, Conservative MP Sir Roger Gale said: "'Bring a bottle' to a 'work event' is a novel idea! Very thin ice indeed."
But fellow Tory backbencher Sir Christopher Chope said it was "monumental relief" that the PM had answered the "basic question" about whether he was at the party or or not.
He told the BBC's Politics Live that the PM was "genuinely sincere" in his apology and he had "realised that he had done the wrong thing".