Speaking following a meeting of the Cabinet Boris Johnson said the Government reserves the “possibility of taking further action” to protect public health due to the spread of the Omicron variant.
The Prime Minister added they were monitoring the situation “hour by hour”.
“Unfortunately I must say to people that we will have to reserve the possibility of taking further action to protect the public, to protect public health, to protect our NHS,” he said.
“We won’t hesitate to take action.”
The PM’s comments come after the Government’s chief scientific adviser Sir Patrick Vallance and England’s chief medical officer Professor Chris Whitty briefed an unscheduled meeting of the Cabinet this evening.
Downing Street denied it was an emergency meeting, saying ministers were being updated on a fast-changing situation.
It follows the Government’s Scientific Advisory Group for Emergencies (Sage) warned daily hospital admissions could reach 3,000 without further restrictions.
Boris Johnson, asked about the prospect of new restrictions including on the hospitality sector, told reporters: “We are looking at all kinds of things to keep Omicron under control and we will rule nothing out.
“But at the moment what I think we want people to focus on is exercising caution so ventilation, masks in the appropriate places, all the usual stuff about washing hands, but remember how contagious Omicron really is.
“I think what you’re seeing already is the British public understanding that and you can see in people’s patterns of behaviour since we went to Plan B that they are changing the way they go about their lives, they are changing some of the assumptions they make about the things that they want to do.”
Johnson also said “in many ways I regret” the impact on hospitality of Plan B and people socialising less, but added: “If it can help to get down the R (rate of infection), get down the way the disease is multiplying, that can be very helpful to us and the country.
“But what really matters is for everybody to get vaccinated and get boosted above all because the booster really does give you a very high level of protection.”
The Government has said that it will if necessary recall Parliament to allow MPs to vote on any new regulations it proposes for England.
However, that could prove politically problematic for Mr Johnson, with senior and junior ministers alike objecting to any further controls.
Last week Mr Johnson suffered the biggest backbench rebellion of his premiership with 100 Tory MPs voting against rules requiring Covid passports for entry into nightclubs and other venues.
Any additional proposals could spark another revolt at a time when the Prime Minister is politically weakened by the ongoing row over parties in Downing Street last Christmas and the Tories’ crushing defeat in the North Shropshire by-election.