British Prime Minister Boris Johnson defied pressure Monday to tighten coronavirus rules over Christmas to curb surging Omicron cases, but vowed to keep the situation "under constant review".

The embattled leader, who is reeling from weeks of crises over various scandals and is facing mounting disquiet within his ruling Conservative party, said "the possibility of taking further action" remained.

However, after a Cabinet meeting, Johnson said ministers had decided not to limit social interactions over the imminent festive period -- despite the government's scientific advisers urging such action.

"In view of the balance of risks and uncertainties, particularly around the infection hospitalisation rate of Omicron... we agreed that we should keep the data from now on under constant review, keep following it hour by hour," Johnson said shortly after.

"We will have to reserve the possibility of taking further action to protect the public and to protect public health and protect our NHS (National Health Service) -- and we won't hesitate to take that action.
"We're looking at all kinds of things to keep Omicron under control and we will rule nothing out, but at the moment we want people to focus on exercising caution."

Britain reported another 91,743 cases on Monday as the new variant rages, with the highest number of infections in London, where hospitalisation rates are also climbing.

Daily case rates have repeatedly broken records over the last week as the country -- one of Europe's worst-hit by the virus, with more than 147,000 deaths during the pandemic -- struggles to contain Omicron.