Sir Keir was filmed drinking a bottle of beer in the constituency office of Durham MP Mary Foy in April last year, in the run-up to a by-election in nearby Hartlepool.
Under rules in place at the time, it was illegal for people in England to socialise indoors with people from outside their household or support bubble.
I don't see how being caught drinking beer in your break with people outside of your bubble can be brushed under the carpet, he gave Boris hell at every opportunity for breaking the rule (rightly so) but if it turns out he was throwing stones in his own glass house he will have to go.
Former shadow home secretary Diane Abbott says Sir Keir Starmer should consider his position as Labour leader if he is fined for breaking Covid laws.
Durham police are investigating whether rules were broken at an event in the city last year where he was pictured drinking beer in an MP's office.
Labour MP Ms Abbott insisted she didn't think he would be fined, and criticised "hype built up by the Tory press".
Sir Keir said he was confident he had not broken any rules.
Asked whether he would resign if fined, he told reporters on Saturday: "I was working in the office. We stopped for something to eat. There was no party".
He added he would lead Labour into the next general election.
But Education Secretary Nadhim Zahawi accused Sir Keir of hypocrisy, given his previous calls for Boris Johnson to resign over lockdown parties in No 10.
Sir Keir was filmed drinking a bottle of beer in the constituency office of Durham MP Mary Foy in April last year, in the run-up to a by-election in nearby Hartlepool.
Under rules in place at the time, it was illegal for people in England to socialise indoors with people from outside their household or support bubble.
Durham police
initially decided no offence had occurred after reviewing footage from the gathering earlier this year.
But after Thursday's local elections concluded, the force announced it would launch an investigation after receiving "significant new information".
The force had been coming under pressure to revisit the matter after Mr Johnson, his wife Carrie and Chancellor Rishi Sunak were fined for attending a birthday party for the prime minister in Downing Street in June 2020.
Conservative MPs and cabinet minister Anne-Marie Trevelyan had also been calling for the force to launch a formal probe in recent days.
'Working incredibly hard'
Labour said last week Angela Rayner
was at the event, having previously denying she was there and blaming a "mistake" in communication.
Questioned about the prospect of Sir Keir being fined on LBC radio, Ms Abbott said: "I don't think he will - I think this is a lot of hype built up by the Tory press.
"But if he were to get a fixed penalty notice, he would have to consider his position," added the Hackney North and Stoke Newington MP, who served as shadow home secretary under former leader Jeremy Corbyn.
"I'm a loyal supporter of Keir Starmer. I'm just making the common-sense point that if he gets a fixed penalty notice he should consider his position."
Shadow health secretary Wes Streeting told the BBC he would not "entertain" the prospect of Sir Keir resigning, adding: "I have absolute faith and confidence that Keir Starmer did the right thing all the way along".
He said police had found "no case to answer" for Sir Keir previously, and "we expect that to be the outcome now".
Labour mayor of London Sadiq Khan said Sir Keir had been eating after "working incredibly hard all day" - and this was "a million miles away from what Boris Johnson was found to have done".
'Hypocrisy'
Sir Keir has called on Mr Johnson to resign since January, when the prime minister became embroiled in accusations Covid rules were broken during gatherings held in Whitehall during lockdown.
Metropolitan Police are continuing their investigation into 12 gatherings held in Downing Street and the Cabinet Office during 2020 and 2021.
Speaking to reporters on Friday, the Labour leader said he had "stopped for something to eat" during work meetings in Durham, and that there was no party - adding he was "confident" he had broken no rules.
Asked what Sir Keir should do if he is fined, Education Secretary Nadhim Zahawi told Times Radio: "We've got to let the police carry out their investigation and that's only right and responsible.
"I do think, though, that the public will be uncomfortable with the hypocrisy.
"He has tweeted himself saying that if you're under investigation, a criminal investigation, then you should resign."
https://www.bbc.co.uk/news/uk-politics-61362474