Prime Minister Boris Johnson has urged people to keep Christmas celebrations "short" and "small" to reduce the risk of spreading Covid over the festive period. Restrictions will still be relaxed between 23 and 27 December - but the PM said people should "think hard" before meeting friends and family.

In Wales only two households - plus an additional single person who lives alone - will be allowed to meet by law. And in Scotland people are being asked to only meet on one of the five days.

The PM said the law was remaining the same in England but "a smaller Christmas is going to be a safer Christmas and a shorter Christmas is a safer Christmas.

“When we say three households can meet on five days, I want to stress, these are maximums, not targets to aim for, and it's always going to be safest to minimise the number of people you meet," he told a Downing Street press conference.

"If that means you're visiting others, we're asking you, for the five days beforehand, as early as Friday, to reduce the number of people you're in contact with to the lowest possible." He also advised people to avoid travelling from "high prevalence" areas to those with lower rates of coronavirus and not to stay away from home overnight if possible.

The PM urged caution over seeing elderly or vulnerable relatives. "Remember, the vaccine is on the way and our aim is to inoculate everyone who's extremely vulnerable, or elderly, by the early months of next year," he said. "If you have an elderly relative, you might want to delay seeing them until they've been vaccinated."

"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. And England's chief medical officer Prof Chris Whitty warned: "Just because you can do something doesn't mean it's sensible in any way."

"Any kind of period where people come together in groups that otherwise wouldn't meet leads to an increase in risks and that will lead to an increase in hospitalisations and deaths," he said. He urged people to keep their Christmas celebrations small, short and local to reduce these risks.

UK leaders had come under pressure to review the guidance for Christmas amid rising infections.

Wales has announced it will head back into a stay-at-home lockdown as soon as the Christmas period is over. Scotland's First Minister, Nicola Sturgeon, said her "strong recommendation" was to "spend Christmas in your own home with your own household", and if people do mix with others they should only do so for one of the five days.

She added: "We will set out advice if you are living in any of the nations in one of the highest level of protection - which in England and London is tier three - then we don't think you should be travelling to other parts of the UK."

Northern Ireland's First Minister Arlene Foster said she would wait to hear from her health minister before announcing changes, but added people must take "all and every precaution" over the festive period. Deputy First Minister Michelle O'Neill said she recognised governments needed to provide "flexibility" over Christmas and that people needed to take personal responsibility for their actions.

The four UK nations previously agreed a set of rules for the festive period, which has been set down in legislation and is not expected to change in England, Scotland and Northern Ireland - even though the guidance has been updated.

·         Between 23 and 27 December, you can form a "Christmas bubble" comprised of people from three households

·         You can travel between tiers and between UK nations to meet your bubble

·         You can only meet in homes, places of worship or public outdoor spaces - not pubs or restaurants

·         You can meet people outside your bubble according to your local rules

But in Wales new guidance on households mixing will be put into law, meaning only two households - plus an additional single person who lives alone - will be able to form a Christmas bubble.

Shadow health secretary Jonathan Ashworth said Labour would support tougher restrictions over Christmas.

"We would have liked to have seen a toughening up today from the prime minister - perhaps something like what we've seen in Wales, reducing households," he said. "I think he's going to have to go further in the coming days."

An information campaign is expected to be launched in the days running up to Christmas, with people being urged to think carefully before bubbling with elderly or at-risk relatives.