Boris Johnson can be seen raising a glass at a leaving party in Downing Street during the second coronavirus lockdown.
ITV News obtained four images showing the Prime Minister with a drink in his hand while he stands behind a table littered with wine bottles and food.
The broadcaster said the pictures were taken at a leaving party for then-director of communications Lee Cain on November 13 2020.
Eight days earlier, Mr Johnson had imposed England’s second national lockdown, which lasted four weeks. People were banned from social mixing, other than to meet one person outside.
Mr Johnson was not fined by the Metropolitan Police over the event seen in the images, which show at least nine people in close proximity along with six bottles of wine.
Downing Street declined to defend the scene portrayed, saying the Prime Minister will comment after the Sue Gray report into partygate is published in the coming days.
A No 10 spokeswoman said: “The Cabinet Office and the Met Police have had access to all information relevant to their investigations, including photographs.
“The Met have concluded their investigation and Sue Gray will publish her report in the coming days, at which point the Prime Minister will address Parliament in full.”
Mr Johnson told MPs in December that “the rules were followed at all times” when asked during Prime Minister’s Questions about Mr Cain’s leaving party.
Deputy Labour leader Angela Rayner accused Mr Johnson of lying over rule-breaking parties at Downing Street.
She said: “While the British public were making huge sacrifices, Boris Johnson was breaking the law.
“Boris Johnson said repeatedly that he knew nothing about law-breaking – there’s no doubt now, he lied. Boris Johnson made the rules, and then broke them.
“The Prime Minister has demeaned his office. The British people deserve better. While Labour has a plan for tackling the cost-of-living crisis, Tory MPs are too busy defending the indefensible actions of Boris Johnson.”
Liberal Democrat deputy leader Daisy Cooper said the images show Mr Johnson “has taken the British people for fools” as she called for Tories to remove him from office.
“It’s becoming clearer than ever that Boris Johnson lied to the British people and to Parliament,” she said.
“Conservative MPs must do their duty and sack this law-breaking Prime Minister. Every day he remains in office will do more damage to public trust and to our democracy.”
On December 8, Labour MP Catherine West asked Mr Johnson in the Commons whether there had been a party in Downing Street on November 13 2020.
The Prime Minister replied: “No, but I am sure that whatever happened, the guidance was followed and the rules were followed at all times.”
The images show Mr Johnson standing closely with seven others in one image.
Including the photographer and the Prime Minister, that makes at least nine people in the room.
Six wine bottles are on the table, one is clearly half empty.
ITV described Mr Johnson as holding half a glass of fizz in the images, while a ministerial red box is perched on a chair in front of him.
The Prime Minister only received one fine during the Met’s investigation, for the gathering for his 56th birthday in June 2020.
Scotland Yard did issue a fine to at least one individual who attended a gathering on the date of Mr Cain’s leaving do, but the force declined to say what the offending event was.
But it was clear the breach, or breaches, were in relation to restrictions on indoor gatherings consisting of two or more people.
The Metropolitan Police declined to explain why the Prime Minister was not fined over the leaving party.
The Commons Privileges Committee is due to investigate whether Mr Johnson lied to Parliament with his denials of rule-breaking.
Intentionally misleading the House would normally be a resigning matter.