Boris Johnson has urged the public to have a “smaller Christmas” than the Covid rules allow.
As it stands, three households are able to form a Christmas bubble over five days, from December 23 to December 27, in England.
But, speaking at a Downing Street press conference on Wednesday, the prime minister called on everyone “to exercise extreme caution” and the “greatest possible personal responsibility”.
“A smaller Christmas is going to be a safer Christmas and a shorter Christmas is a safer Christmas,” he said.
Johnson stopped short of legally changing the rules, saying it would be “frankly inhuman and against the instincts of many” to effectively “ban Christmas”.
But he issued new advice, telling people to reduce contact with others from this Friday and cut down the time spent with others over Christmas.
People planning to see families at Christmas should avoid travelling from “high prevalence” areas to those with lower coronavirus case rates and not to stay overnight if possible, he said.
He further suggested people should delay seeing an elderly relative until they have been vaccinated, avoid going to crowded Boxing Day sales, and not gather in large groups indoors to celebrate New Year.
Chief medical officer Chris Whitty, who appeared alongside the PM, said: “Keep it small, keep it short, keep it local, and think of the vulnerable.”
Wales and Scotland have issued stronger guidance for the festive season, however.
First minister of Wales Mark Drakeford said people should stick to a limit of two, rather than three, households could form a Christmas bubble.
The Scottish government, meanwhile, has advised that a bubble of no more than two households should not meet up for more than a day and avoid staying overnight together.
Johnson said the government was forced to act amid a rise in coronavirus infections in recent days.
He said: “When we say three households can meet on five days I want to stress these are maximums and not targets to aim for.
“It’s always going to be safest to minimise the number of people you meet. That means if you are visiting others over Christmas we’re asking you in the five days beforehand, as early as this Friday, to reduce the number of people you are in contact with to the lowest possible.
“If possible don’t travel from a high prevalence to a lower prevalence area and avoid staying away from home overnight if you can.”
He went on: “And whatever your plans for Christmas, please think carefully about avoiding crowds in the Boxing Day sales.
“And no one should be gathering in large groups to see in the new year.”
He added: “If you have an elderly relative you might want to delay seeing them until they have been vaccinated.”