Millions of Londoners will face tougher Tier 2 Covid measures from Saturday, with a ban on households mixing indoors, the health secretary has said.
Essex and other areas will also move to high-alert restrictions this weekend, Matt Hancock said.
Under Tier 2, households are also barred from mixing in pubs and restaurants.
It comes as a final decision has yet to be made on whether Greater Manchester will move into the highest Tier.
The areas to go into high alert restrictions this weekend are:
Elmbridge in Surrey
Barrow in Furness, Cumbria
North East Derbyshire
Speaking at London's City Hall, Labour mayor Sadiq Khan said there was "simply no other option".
"Nobody wants to see more restrictions but this is deemed to be necessary in order to protect Londoners," he said.
Mr Khan said he is continuing to press the government for more financial support, adding that "we've got a difficult winter ahead".
The London mayor also backed calls by Labour leader Sir Keir Starmer for a temporary national "circuit-breaker" to stem the spread of the disease.
Labour shadow minister and Ilford North MP Wes Streeting said the new restrictions in London would keep businesses open "in name only" as he called for more economic support.
The tier change means the capital's 3,640 pubs and 7,556 restaurants will not be eligible for government support available to premises which have been ordered to close.
Mr Streeting said: "There are lots of restaurants, pubs, bars and other venues whose doors will be open but customers will just not be walking through the door."
Robert Halfon, the Conservative MP for Harlow in Essex, said he would welcome Tier 2 measures for the county but would call on Chancellor Rishi Sunak to prevent businesses suffering financially from the move.
He said: "The key issue is if we don't do this now we could face the much higher restrictions in a few weeks which would be even worse for businesses."
But Rupa Huq, Labour MP for Ealing Central and Acton in west London, tweeted that she was "unconvinced this tinkering is really enough" and called for a circuit-breaker to stop the disease "spreading like wildfire".
Ministers being briefed on restrictions
have been briefed over the new measures in a call with health minister Helen Whately.
The new three-tier system sees every area of England classed as being on medium, high or very high alert.