Boris Johnson will spend the weekend considering whether to tighten Covid-19 measures further, after saying the UK was “now seeing a second wave”.
The government is understood to be looking at a ban on households in England mixing, and reducing opening hours for pubs and restaurants.
At least 13.5 million people, roughly one-in-five of the UK population, are already facing local restrictions.
In London, additional measures were “increasingly likely”, its mayor said.
Mr Johnson only has direct power over restrictions in England. The devolved governments in Scotland, Wales and Northern Ireland can set their own rules.
Widespread growth of the virus has been recorded across the country, with cases doubling every seven to eight days.
There were a further 4,322 confirmed cases on Friday – the first