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.
Mr 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," Mr Johnson said in the first Downing Street coronavirus briefing since July.
He added "it breaks my heart to have to insist on these restrictions".