London, Dec 9 (IANS): A UK government adviser has resigned following a backlash over a video that showed her joking about an alleged Christmas party at Downing Street last year while London was under strict Covid-19 restrictions.

On Wednesdaym Allegra Stratton said she has offered her resignation less than 20 hours after the video emerged, reports Xinhua news agency.

The video, obtained by ITV, showed Stratton, who was Prime Minister Boris Johnson's Press Secretary at that time, laughing about how to describe the alleged party during a rehearsal for a news conference.

In the footage from December last year, Stratton and other senior aides can be heard jokingly referring the party to a "business meeting" and a "cheese and wine" event.

In her statement on Wednesday, she said the British people had made immense sacrifices and apologised for comments that "seemed to make light of the rules".

"I will regret those remarks for the rest of my days and offer my profound apologies to all of you for them," she said.

But she did not mention in the statement whether the party did actually happen.

Johnson also apologised for the video in Parliament on Wednesday, saying that he was "furious" about the clip and was launching an investigation into whether rules had been broken.

But opposition Labour leader Keir Starmer said the Prime Minister had taken the public for fools as Downing Street has refused during the past week to confirm what happened at the alleged party on December 18 last year.

Matt Fowler, co-founder of the Covid-19 Bereaved Families for Justice, accused the Prime Minister of trying to "gaslight" bereaved families.