LONDON — U.K. Prime Minister Boris Johnson is facing calls to resign over reports that members of his staff attended a Christmas party last year while the country was in lockdown.

The Daily Mirror newspaper reported that the party took place on Dec. 18, 2020, which would have been illegal under the coronavirus restrictions in place at the time. Johnson has denied the allegation.

In a video leaked to ITV News, the prime minister’s press secretary can be heard joking about a Christmas Party, four days after the party was alleged to have taken place.

In the video, the prime minister’s press secretary and other staff members can be seen holding a mock press conference, discussing how they would respond to allegations that Downing Street had held a Christmas party.

“It wasn’t a party, it was cheese and wine,” one person can be heard saying, prompting laughs across the room. The leaked video prompted fury from opposition lawmakers and residents alike.

Allegra Stratton, the staff member seen in the video, resigned from her post on Wednesday.

At a weekly scheduled parliamentary session on Wednesday, Johnson repeatedly denied that a party had taken place, but he did apologize for the leaked video, saying: “I was also furious to see that clip … I apologize unreservedly for the offense it has caused up and down the country.”

Johnson said he had ordered an internal investigation into the incident, but the leader of the opposition Labour Party, Sir Keir Starmer, has called for evidence to be handed over to the police, saying the prime minister had taken the British public for “fools.”

“Her Majesty the Queen sat alone when she marked the passing of the man she’d been married to for 73 years,” Starmer said. “Leadership, sacrifice – that’s what gives leaders the moral authority to lead. Does the prime minister think he has the moral authority to lead and to ask the British people to stick to the rules?”

Further fallout could be on the horizon, with one lawmaker asking the prime minister about another party that may have taken place on Nov. 13, which Johnson also denied. As of June 2021, a month before social distancing measures were fully relaxed in England, a total of 366 fines had been issued in England and Wales for large gatherings, according to the National Police Chiefs’ Council.

Critics of the prime minister say the video threatens to undermine public trust in the government, particularly at a time when new restrictions are set to be introduced to combat the spread of the omicron variant. One lawmaker, from Johnson’s own Conservative Party, went as far to suggest that the possible new restrictions, reported before the fiery exchange in Parliament, were a “diversionary tactic.”