Nicola Sturgeon has told Scots to limit socialising with a maximum of three households at a time in the run-up to Christmas.
The First Minister said new "strong guidance" was needed to curb the spread of Covid as Scotland faces a "tsunami" of Omicron cases in the weeks ahead.
Although the crackdown is guidance not law, it is the first time UK social gatherings have been restricted since spring.
The restrictions on socialising will not apply on Christmas Eve, Christmas Day or Boxing Day.
And the SNP leader did not urge people to limit the number of people they see within each household.
But she warned Omicron cases are “increasing exponentially – faster than any variant that has gone before it”.
Insisting she is not asking Scots to cancel Christmas, Ms Sturgeon asked people to minimise social mixing, as she waits to issue guidance to help on how people can make their festive gatherings safer.
Pubs, restaurants and shops will also have to take measures to reduce crowds and queues, Ms Sturgeon said.
She told MSPs there would be a "return to the kind of protections in place at the start of the pandemic" to avoid crowding such as physical distancing, table service and contact tracing in bars, pubs, cafes and restaurants.
When asked if Boris Johnson will follows Ms Sturgeons lead, the Prime Minister's spokesman stopped short of telling people to limit their social interactions before Christmas.
He said: “We would urge people who are going to be seeing loved ones or spending time otherwise indoors with people, particularly those who might be more vulnerable to this, to get tested beforehand, to access testing, to use ventilation, to use good hand respiratory hygiene, wash your hands, and that is the advice that we give to the public at this time.”
The tougher Covid restrictions for Scots come just a week after Ms Sturgeon said she hoped she wouldn't have to impose new Covid measures, but stressed she could not guarantee it.
Speaking today at Holyrood as she made her Covid-19 statement to MSPs, Ms Sturgeon said: “My key request today is this: before and immediately after Christmas, please minimise your social mixing with other households as much as you can.
“However, if you do plan on socialising, either at home or in indoor public places, we are asking that you limit the number of households represented in your group to a maximum of three. And make sure you test before you go.”
If Scots are keen on still meeting loved ones in the run up to the holidays, she urged them to make sure they are jabbed, and if they do meet indoors, they should make sure rooms are well ventilated.
It comes after Scotland’s Health Secretary Humza Yousaf warned new restrictions were “inevitable” because of the Omicron strain.
Scotland recorded 26 new cases of the Omicron variant on Monday, taking the overall number to 186, while a further 3,756 Covid-19 cases were confirmed.
