UP to three households will be allowed to form a Christmas “bubble” and mix over the festive season, in a UK-wide plan agreed by ministers and the devolved nations.

The “cautious and limited relaxation of the rules” between December 23 and December 27 will also allow people to travel between local authorities and between Scotland, England, Wales and Northern Ireland.

Nicola Sturgeon urged Scots to consider carefully whether the opportunity to mix for a few days was necessary. She admitted that even this short relaxation of the rules would “give the virus a chance to spread” and said that this change would not apply to Hogmanay.

The First Minister said: “We know that for some, contact with friends and family is crucial during this time as isolation and loneliness can hit people especially hard over the Christmas period.

“The ‘bubble’ approach aims to reduce this impact.

“But we must be clear, there cannot be any further relaxation of measures for Hogmanay. Even this short relaxation will give the virus a chance to spread. Our priority is to suppress transmission of Covid-19 and reduce the risk to the vulnerable and those who have spent so long shielding – and that involves abiding by the rules.

“Just because you can mix with others indoors over this time, that doesn’t mean you have to.

“If you choose to stick with the rules as they are, then you will be continuing the hard work to beat this virus and prevent its spread.”

Under the new guidance, which was signed off at a meeting of Cobra yesterday afternoon, people will be allowed to form an exclusive bubble between a maximum of three households. There will be no social distancing within bubbles, so families can hug and shake hands and sit next to each other at the dining table.

These bubbles can gather in a home, an outdoor place or a place of worship. However, they can’t gather in pubs or leisure venues.

Households deciding to form a bubble will be urged to limit social contact before and after the period of relaxation.

However, you’ll need to choose your bubble wisely as you’ll only be allowed to join the one. There’ll be no bubble mixing.

The Scottish Government has also urged households not to use all five days if they can help it and to try and keep visits to no more than one or two days if possible.

There are some variations to the rules. In England, house sharers will be able to disperse to different family homes as separate household bubbles, in Scotland they will count as the same household.

Earlier, in the day giving evidence to a Commons committee, Devi Sridhar, the professor of global public health at the University of Edinburgh, and a key advisor to the Scottish Government, said the relaxation was risky.

“People emotionally want to hear reassuring messages,” she said. “They wanted to hear it over the summer that there would be no second wave, and they want to hear it now that Christmas will be normal.

“I guess I have to speak bluntly: the virus doesn’t care if it’s Christmas. We still have pretty high prevalence across the country.

“It is risky for people to mix indoors with alcohol with elderly relatives at this point in time.”

In Holyrood, the Scottish Greens demanded that evidence is published to set out how much progress in suppressing the virus could deteriorate if rules are relaxed at Christmas.

Co-leader and health spokesperson, Alison Johnstone. said: “We all very much understand that any loosening of restrictions over Christmas is a trade-off. Will the First Minister ensure that the Scottish Government publishes the evidence base behind the arrangements, and can she ensure that that includes modelling of the impact that the arrangements will have on the number of new infections over the Christmas period? For example, what level of increase in infection will be considered acceptable?”

Sturgeon said the government would continue to “publish evidence and modelling, as we think that that is helpful and appropriate”.

She added: “We are seeking to give people the option, should their personal circumstances require it, of a bit of flexibility over Christmas, whether that is providing a window of time or some flexibility in the number of households that can come together.

“What we are absolutely not doing is encouraging everybody to go out and use that to the maximum.”