LONDON: British Prime Minister Boris Johnson faced criticism on Wednesday after a video surfaced showing his staff laughing and joking over how to explain a gathering in Downing Street during a COVID lockdown last Christmas when such festivities were banned.

Johnson and his ministers have repeatedly denied any rules were broken by the gatherings in late 2020, though the Mirror newspaper said Johnson spoke at a leaving party, and that his team had a wine-fuelled gathering of around 40 to 50 people.

But in a video aired by ITV, Allegra Stratton, who was then Johnson's press secretary, was shown at a 2020 Downing Street rehearsal for a daily briefing laughing and joking about the gathering.

The furore comes as the government is weighing up whether to impose new restrictions on the public to try to beat back the new coronavirus variant Omicron.

It follows a string of scandals that have led opposition politicians to accuse the Johnson government of cronyism and corruption, and of behaving as if rules do not apply it.

In the video, a Johnson adviser asks Stratton: "I've just seen reports on Twitter that there was a Downing Street Christmas party on Friday night — do you recognise those reports?"

Stratton, standing before British flags at an official Downing Street lectern, chuckles and says: "I went home." She then laughs and smiles.

"Hold on. Hold on. Um. Er. Arh." She appears lost for words and looks up.

Newspapers were universally critical.

"A sick joke," read the banner headline on the Daily Mail, Britain's biggest selling newspaper. "No. 10 Party Clowns" said Metro. The Guardian said: "PM accused of lying after No 10 team filmed joking about party."

Conservative Party lawmaker Roger Gale said that if the House of Commons had been deliberately misled over the party then it would be a resignation matter.

The leader of the opposition Labour Party, Keir Starmer, said the video was an insult to those who had followed lockdown rules when it meant being separated from their families over Christmas.

"They had a right to expect that the government was doing the same. To lie and to laugh about those lies is shameful," Starmer said in a statement. "The prime minister now needs to come clean, and apologise."

Ian Blackford of the Scottish National Party, the second-biggest opposition party in parliament, called for Johnson to step down.