Boris Johnson has refused to say whether he attended a lockdown breaking party at Downing Street, after new claims emerged.
The prime minister on Monday morning dodged questioning about whether he and his wife Carrie attended the gathering in May 2020.
The get-together was allegedly organised by Mr Johnson's principal private secretary Martin Reynolds – who it was reported on Sunday might be lined up to be the "fall guy" for the episode.
Labour leader Keir Starmer said Mr Johnson would have "serious questions to answer" if found to have attended the party.
The Sunday Times alleged the Prime Minister attended the event in the No 10 garden with Mrs Johnson, citing three sources who referred to an email from Mr Reynolds which say "BYOB", meaning "bring your own bottle".
Asked if he attended, the Prime Minister told reporters: "All that, as you know, is the subject of a proper investigation by Sue Gray."
Pressed on the subject he added: "All that is a subject for investigation by Sue Gray." No.10 also denied reports Mr Reynonds would be moved from his current role.
A spokesperson gave a similar response when asked about Mr Johnson's attendance, adding: "There is an independent process going on to look into this, led by Sue Gray, and I can't comment further while that is taking place."
Opposition chief Sir Keir was asked on Monday morning whether Mr Johnson would have to resign if found to have attended the bash, and added: "We need to let the inquiry take its course, see what the findings are.
"The prime minister has insisted he broke no rules so if the finding is that he did then he will obviously have very serious questions to answer.
"Let's let the inquiry play out, let's see what the findings are and then go from there."
The Labour chief added: "The Prime Minister has lost huge authority with the public because of these allegations of parties in Downing Street.
"To stand at a press conference, instructing the country to comply with restrictions - which really impacted families across the country - whilst at the same time there's emerging evidence of parties in Downing Street does diminish his authority, his moral authority, to ask others to comply with those rules.
"That's why it's so damaging - it's not just a matter of history, it's a matter of the here and now."
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