London has tightened restrictions after coronavirus cases skyrocketed across the UK capital, the government has confirmed.
The new measures, set to come into effect from 00.01 on Saturday morning, will ban different households from gathering indoors and will advise against the use of public transport.
Pubs and restaurants will be able to stay open, but households cannot mix and establishments will need to stick to a 10 pm curfew.
Meetings in private gardens and other outdoor spaces will also be limited to groups of six people - a measure dubbed the "rule of six" in the UK.
Confirming the changes, Health Secretary Matt Hancock said the situation remained "grave and serious" as COVID-19 continued to "spread exponentially" across the UK.
He said cases in the capital - a city of 9 million people - had been doubling every ten days and had prompted "vital" rules to be put in place.
"We make these decisions with a heavy heart," Hancock said, warning that things would "get worse before they get better".
Urging Londoners to "work together", he added: "We all need to play our part in getting the virus under control once again".
Earlier on Thursday, London mayor Sadiq Khan said he understood new measures were unwanted, but stressed they were necessary to stop transmission.
He told the London Assembly: "Nobody wants to see more restrictions - but this is deemed to be necessary in order to protect Londonders' lives by myself, London council leaders and by ministers."
The UK capital has a current case rate of 97 infections per 100,000 people - but Khan warned a "significant number" of individual boroughs were now reporting over 100.
COVID-19 is "spreading rapidly in every corner of our city," he added, urging the government to go further than their localised restrictions and enact a nationwide lockdown.
The London mayor is the latest person to encourage Boris Johnson to impose a two-to-three week "circuit break" lockdown to stem the spread of the virus.
Among such calls has been Labour leader Sir Keir Starmer who accused the prime minister on Wednesday of falling "behind the curve again".
He said: "Having read and considered the SAGE advice, I have concluded a circuit break is in the national interest.
"It is the failure of the prime minister's strategy that means tougher measures are now unavoidable.
"That's SAGE's view."
The Scientific Advisory Group for Emergencies (SAGE) - the government's group of advisers - had earlier recommended the short circuit breaker lockdown; however, Johnson has continued to insist on following his regional tiered approach to tackling the virus.
"The difference between this stage of the pandemic from March and April is that the disease is appearing much more strongly in parts of the country than in others," Johnson said.
Comparing Liverpool, which has 676 cases per 100,000 people, to Cornwall, which has 33 cases per 100,000, he stressed his approach was "the right way forward".
"We want to put in the most stringent measures necessary in the places where the virus is surging in order to get it down where it is surging.
"That is the logical thing to do."