Boris Johnson has urged people to limit their social contact “as much as possible” and to minimise interactions with other households as he outlined new measures to control a surge in coronavirus cases.

The Prime Minister said he was “sorry” that two households that exceed six people would no longer be able to meet in England from Monday, and said he wished that he did not have to take such steps.

But addressing the first Downing Street press conference since July, Mr Johnson said that “if we are to beat the virus then everyone, at all times, should limit social contact as much as possible”.

“It is safer to meet outdoors and you should keep your distance from anyone you don’t live with, even if they are close friends or family.”

He said that under the new “rule of six” people “must not meet socially in groups of more than six – and if you do, you will be breaking the law”.

“This will apply in any setting, indoors or outdoors, at home or in the pub. The ban will be set out in law and it will be enforced by the police – anyone breaking the rules risks being dispersed, fined and possibly arrested.”

The Prime Minister said the new rules were being introduced to “prevent another wholesale national lockdown”, and said he was “still hopeful” that “we could be able to get some aspects of our lives back to normal by Christmas”.

He also announced:

– Venues where people meet socially, such as pubs and restaurants, will be legally required to request contact details of every member of a party and retain the information for 21 days. Fines of £1,000 could be levied against hospitality venues if they fail to comply.

– Passengers travelling to the UK will need to fill out a simplified form with their contact details before they depart, while the Border Force will step up enforcement efforts to ensure compliance with quarantine rules.

– Plans to pilot larger audiences in venues later this month will be revised, and the Government is reviewing its intention to return audiences to stadiums and conference centres from October 1.

– Opening hours of some venues could be restricted in some local areas. It comes after hospitality venues in Bolton were required to close between 10pm and 5am.

– “Covid-secure marshals” will be introduced to help ensure social distancing in town and city centres in a bid to improve the enforcement capacity of local authorities.

The new rules follow a rise in cases from 12.5 per 100,000 people to 19.7 per 100,000 in the UK in the last week – with a particular rise in infections among young people.

Infections are most prevalent among the 19 to 21-year-old age group, with 54 cases per 100,000 people.

The uptick suggests the national R number is now above 1 – meaning the virus is spreading exponentially.

England’s chief medical officer, Professor Chris Whitty, warned the period between now and spring will be “difficult” but said that with decisive action there is a “good chance” of bringing rates back down under control.

He said there had been “rapid upticks” in cases among some age groups, but that in school aged children and older people the number of infections remained “flat”.

Mr Johnson also used the press conference to outline plans to use testing to identify people who do not have coronavirus, so they can “behave in a more normal way, in the knowledge they cannot infect anyone else with the virus”.

The “moonshot” plan, the Prime Minister said, could enable theatres and sports venues to test audience members on the day and allow in all those testing negative, as well as enable workplaces to operate more normally.

It would use swab or saliva tests that can turn around results in 90 or 20 minutes. Mr Johnson said he hoped “literally millions of tests” could be processed every day.

The approach will be piloted in Salford from next month, with audiences in indoor and outdoor venues, and then the Government hopes “to go nationwide”.

Labour leader Sir Keir Starmer said his party supported the “principle of the measures and we ask everybody to follow those rules”.

The British Medical Association said: “It now seems illogical, with infections remaining above 2,500 a day, to delay the new measures around social gatherings until after the weekend, when people will want to meet up, and risk spreading the virus further.”