British Prime Minister Boris Johnson faced a parliamentary reckoning Wednesday about another alleged breach of coronavirus rules that has prompted damning headlines and calls for him to quit.

Johnson is under fierce pressure to say whether he attended a boozy gathering in the garden of his Downing Street residence in May 2020, in the midst of the country's first strict lockdown.

It follows a flurry of accusations about Downing Street parties held during lockdowns in 2020 which have dogged Johnson since late last year, sparking widespread public anger, sinking poll ratings and predictions he may have to resign -- even from his own MPs.

"If the prime minister knowingly attended a party I don't see how he can survive, having accepted resignations for far less," Conservative lawmaker Nigel Mills told the BBC.

Johnson, elected by a landslide in December 2019, will be quizzed for the first time on the latest claims by opposition Labour leader Keir Starmer and other MPs at weekly parliamentary questions from noon (1200 GMT).

The 57-year-old has stonewalled the issue since an email was leaked late Monday in which a senior official invited more than 100 colleagues to the event on May 20, 2020, encouraging them to "bring your own booze".

Johnson and his wife Carrie attended the gathering, according to anonymous witnesses quoted in the media, intensifying public anger from a time when millions were obediently respecting the lockdown rules.

‘Misled parliament’

Lisa Wilkie was forced to film her brother dying of Covid in intensive care in May 2020, because her mother was not allowed to visit the hospital under the restrictions.

"People died sticking to the rules, and they broke those rules to have a bottle of wine," a tearful Wilkie told the BBC.

The event occurred when the government was ordering members of the public not to meet, even outdoors, and tight restrictions were in place on social mixing, including at funerals.

Police at the time fined those breaching the rules, and had the option to prosecute repeat or egregious offenders.

The latest accusations appear to directly contradict Johnson's prior claims that no lockdown rules were broken in Downing Street.

"Boris Johnson has to account for his actions, and the ministerial code is very clear that if he has misled parliament and he has not abided by that code, then he should go," Labour deputy leader Angela Rayner told the BBC.

Hannah Brady, whose father's death certificate was being signed on May 20, 2020, penned an open letter with other bereaved families whom Johnson has personally met, urging him to "do the right thing" and explain what happened.

'Indefensible'

Even the front pages of newspapers that normally back Johnson and the Tories were damning.

"Is the party over for PM?" asked the best-selling Daily Mail, while the Daily Telegraph's headline said: "Johnson losing Tory support."

"It's my party and I'll lie low if I want to," mocked The Sun tabloid.

Johnson had hoped to start the new year afresh, leaving behind the accusations of lockdown-breaking parties and separate claims of cronyism and corruption that contributed to a shock by-election defeat for the Tories before Christmas.

The party allegations had prompted him to appoint senior civil servant Sue Gray to investigate the spate of claims. Her probe has now been widened to include the latest accusations.

Meanwhile, London's Metropolitan Police have said they have been in contact with the Cabinet Office about the May 2020 gathering, raising the possibility of a more serious, criminal probe.

The ongoing furore appeared to be proving increasingly unbearable for Conservative lawmakers.

"How do you defend the indefensible? You can't!" Tory MP Christian Wakeford tweeted Wednesday.

"It's embarrassing and what's worse is it further erodes trust in politics when it's already low."