LONDON — British Prime Minister Boris Johnson announced tighter restrictions today to stem the spread of the omicron variant, urging people in England to again work from home and mandating COVID-19 passes for entrance into nightclubs and large events.

Johnson said it was time to impose stricter measures to prevent a spike of hospitalizations and deaths as the new coronavirus variant spreads rapidly in the community.

“It has become increasingly clear that omicron is growing much faster than the previous delta variant and is spreading rapidly all around the world,” he said in a press conference. “Most worryingly, there is evidence that the doubling time of omicron could currently be between two and three days.”

Johnson said that 568 cases of the omicron variant have been confirmed across the U.K., and “the true number is certain to be much higher.”

He said beginning next Monday, people should work from home if possible. Starting on Friday, the legal requirement to wear a face mask will be widened to most indoor public places in England, including cinemas. Next week, having a COVID-19 pass showing that you have had both vaccine doses will be mandatory to enter nightclubs and places with large crowds.

Overall, the British government reported another 51,342 confirmed daily cases of COVID-19 in the U.K as of today, with 161 more people dying.

The announcement came as Johnson and his government faced increasing pressure to explain reports that Downing Street staff enjoyed a Christmas party that breached the country’s coronavirus rules last year, when people were banned from holding most social gatherings. Johnson on Wednesday ordered an inquiry and said he was “furious” about the situation.

The revelations have angered many in Britain, with critics saying they heavily undermine the authority of Johnson’s Conservative government in imposing virus restrictions.