UK Prime Minister Boris Johnson has said "we must act" to avoid another lockdown as virus cases rise in England.
He set out a new "rule of six", restricting gatherings to a maximum of six people, enforced by police able to issue fines or make arrests.
Johnson also outlined a "moonshot" plan to control the virus with mass testing, possibly by next spring.
It comes as the UK reported another 2,659 coronavirus cases, the fourth day running of over 2,000 reported cases.
"I want to be absolutely clear, these measures are not another national lockdown. The whole point of them is to avoid a second national lockdown," Johnson said.
He added "it breaks my heart to have to insist on these restrictions".
In the last week, cases have risen from 12.5 infections per 100,000 people to 19.7 per 100,000 across the UK.
Coronavirus was more prevalent among young people, with 54 cases per 100,000 people in the 19 to 21-year-old age group.
Johnson also announced that:
- Venues such as pubs and restaurants will be legally required to request contact details of everyone visiting, hold it for 21 days and provide it to the National Health Service Test and Trace. They face fines of £1,000 if they fail to comply
- Opening hours could be restricted in some areas, as has happened in Bolton, in north west England after a rise in cases, where venues must close between 10pm and 5am
- "Covid-secure marshals" will be introduced to help ensure social distancing in town and city centres
- The passenger locator form, filled out by travellers arriving in the UK to enforce quarantine rules, will be simplified and Border Force will increase enforcement
- Plans to try out larger audiences in venues later this month will be revised, and the government is reviewing its plan to allow spectators back into sports stadiums from 1 October
Johnson said the government was "simplifying and strengthening the rules" after feedback from police and the public.
But Labour leader Sir Keir Starmer said the new rules on gatherings were a reflection that "poor communications were a large part of the problem" with the spread of the virus.
Sir Keir said the government also needed to improve testing, which was "all over the place", following reports that some people have been unable to book tests.
The prime minister said the government was "working hard" to increase testing capacity to 500,000 tests a day by the end of October, but urged people only to book a test if they had coronavirus symptoms.
He said they also want to use new types of test "in the near future" to identify people who do not have coronavirus and are not infectious so they can live life "in a more normal way".
He said these swab or saliva tests could be turned around in 90 or even 20 minutes, with millions processed each day - a "moonshot" effort to restore more normal life even if a vaccine or treatment is not available.
These new tests will be piloted with audiences attending indoor and outdoor venues in Salford from next month.
'The alternative is worse' - chief medical officer
But the government's chief scientific adviser Sir Patrick Vallance said the technology needed to be "tested carefully" and it would be "completely wrong to assume this is a slam dunk".
The measures that needed to be taken against coronavirus were "damaging" socially, economically and to people with other health conditions, chief medical officer Chris Whitty acknowledged.
"We have to do them because the alternative is worse," he said. He added that "the period between now and spring is going to be difficult" and the restrictions were unlikely to be lifted after just two or three weeks.
Johnson said the restrictions would only be in place "as long as necessary".
"I'm sorry about that. I wish we did not have to take this step, but as your prime minister I must do what is necessary to stop the spread of the virus and save lives," he said.
The new "rule of six" means:
- Social gatherings of more than six people in England will not be allowed in law from Monday 14 September
- The new rule applies to people in private homes, indoors and outdoors, and places such as pubs, restaurants, cafes and public outdoor spaces
- It applies to all ages
- The rule does not apply to schools and workplaces, or weddings, funerals and organised team sports
- A full list of exemptions is due to be published before the law changes
- People who ignore the police could be fined £100 - doubling with each offence to a maximum of £3,200
At present, the guidance says two households of any size are allowed to meet indoors or outdoors, or up to six people from different households outdoors. Until now the police have had no powers to stop gatherings unless they exceeded 30.
The number of people allowed to meet inside or outside varies in the UK's four nations. If you are meeting indoors: up to eight people from three different households can meet in Scotland; up to six people from two households in Northern Ireland; up to four households can form an "extended household" in Wales.