British Prime Minister Boris Johnson's staff appeared to joke about holding a Christmas party last year while much of the country faced tough Covid-19 restrictions, in a leaked video released by broadcaster ITV.

Mr Johnson has faced questions and criticism since the Mirror newspaper reported last week there were many social gatherings at Mr Johnson's 10 Downing Street office over the Christmas period.

In the video from 22 December 2020, Mr Johnson's staff hold a mock press conference and appear to joke about holding a Christmas party.

Allegra Stratton, who was Mr Johnson's press secretary and is now his COP26 climate conference spokeswoman, laughs as she fends off questions about a "Downing Street Christmas party on Friday night".

She asks "is cheese and wine alright?" when one staffer suggests it as an alternative to the word "party," before she adds "this fictional party was a business meeting, and it was not socially distanced".

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," Mr Starmer said in a statement.

"The prime minister now needs to come clean, and apologise."

Speaking before ITV released the video, Mr Johnson said he was satisfied that no Covid lockdown restrictions had been broken.

"The guidelines were followed at all times," Mr Johnson told broadcasters on Tuesday.

"I have satisfied myself that the guidelines were followed at all times."

The Metropolitan Police said it is reviewing the footage.

A statement from the force said: "We are aware of footage obtained by ITV News relating to alleged breaches of the Health Protection Regulations at a Government building in December 2020.

"It is our policy not to routinely investigate retrospective breaches of the Covid-19 regulations, however the footage will form part of our considerations."