BORIS JOHNSON confirmed it was time to move to "Plan B" of the Government’s coronavirus strategy, with measures including a return to working from home.

He told a Downing Street press conference: "It has become increasingly clear that Omicron is growing much faster than the previous Delta variant and is spreading rapidly all around the world."

While 568 cases had been confirmed in the UK "the true number is certain to be much higher".

He continued: "Most worryingly, there is evidence that the doubling time of Omicron could currently be between two and three days."

The Prime Minister said that people should work from home if they can as of Monday.

"We will reintroduce the guidance to work from home.

"Employers should use the rest of the week to discuss working arrangements with their employees but from Monday you should work from home if you can.

"Go to work if you must but work from home if you can.

"I know this will be hard for many people but by reducing your contacts in the workplace, you will help slow transmission.”

Boris Johnson told a Downing Street press conference: "We can’t yet assume that Omicron is less severe than previous variants.

"So while the picture may get better, and I sincerely hope that it will, we know that the remorseless logic of exponential growth could lead to a big rise in hospitalisations and therefore, sadly, in deaths.

"That's why it is now the proportionate and the responsible thing to move to Plan B in England while continuing to work closely with our colleagues in the devolved administrations, so we slow the spread of the virus, buy ourselves the time to get yet more boosters into arms, especially in the older and more vulnerable people."

From Friday the legal requirement to wear a face mask will be extended in England to most indoor public venues, such as cinemas and theatres - although there will be exemptions for things such as eating, the PM says.

Covid passes will become mandatory for nightclubs and venues where large crowds gather in England.

This will include unseated indoor venues with more than 500 people, unseated outdoor venues with more than 5,000 people and any venue with more than 10,000 people.

He says two doses will be sufficient for a Covid pass, but this will be kept under review as boosters are rolled out.

A negative lateral flow will also be acceptable.