The new so-called "rule of six" has come into effect in England from Monday, which would give the police the power to enforce rules against gatherings larger than six members with a fine of 100 pounds.
The new rule -- announced by UK Prime Minister Boris Johnson last week amid another spike in coronavirus cases -- applies both indoors and outdoors in England and Scotland, and indoors only in Wales.
"Across the country, we have all made enormous sacrifices in the fight against coronavirus. However, the recent rise in cases makes it clear that more needs to be done to stop the spread of this disease," said UK Home Secretary Priti Patel.
In England, the restrictions affect everyone including young children but for the devolved administrations of Wales and Scotland 11 and 12-year-old children are exempt from the rule.
Other exceptions to the rules mean that many activities involving bigger numbers will still be able to take place, including at schools, workplaces, weddings and funerals with up to 30 people.
The Home Office claims that the "rule of six" simplifies and strengthens the rules on social gatherings, making them easier to understand and easier for the police to enforce.