Gatherings of more than six people will be banned from Monday: £100 fines to enforce new limit on meeting indoors and outdoors across England - but schools, weddings and funerals are exempt
Gatherings of more than six are being banned to try to halt a second wave of coronavirus.
In his first reversal of the easing of national lockdown, Prime Minister Boris Johnson last night warned a surge in cases must not be allowed to get out of control.
From Monday it will be illegal to assemble in groups of seven or more anywhere in England, whether indoors or out.
The "rule of six" is a dramatic reduction on the limit of 30 put in place on July 4.
Police will be encouraged to break up larger groups and issue £100 ($196) fines, which will then double on each repeat offence up to £3200.
Only schools, workplaces and a limited number of other locations will be exempt.
As the move prompted fears a wider and more damaging lockdown might follow.
Announcing the new restrictions, Johnson said: "'We need to act now to stop the virus spreading. So we are simplifying and strengthening the rules on social contact – making them easier to understand and for the police to enforce.
"It is absolutely critical that people now abide by these rules and remember the basics – washing your hands, covering your face, keeping space from others, and getting a test if you have symptoms."
Ministers were shocked on Sunday when virus cases doubled to almost 3000 – the highest figure since May.
They have used local lockdowns to control flare-ups and in Bolton the rules were tightened again yesterday, with a 10pm curfew on hospitality venues and a ban on dining out.
Downing Street said the surge appeared to be driven by "young people, often in affluent areas".
The PM's spokesman said similar outbreaks among the young in the United States and Europe had spread to older people a few weeks later, with deadly effect. He added: "We need to ensure that doesn't happen here."
The clampdown will dismay some Tory MPs who are urging the Government to press ahead with the reopening of society to avoid economic meltdown. But a Government source last night insisted the rule of six was needed to head off the danger of a wider lockdown.
Johnson will underline the message at a press conference this afternoon, where he will be flanked by chief medical officer Chris Whitty and chief scientific adviser Sir Patrick Vallance.
In a sober briefing to the Cabinet yesterday, the two scientists warned ministers the R-rate had risen above one, meaning the virus was spreading exponentially again.
The change will mean an end to large family gatherings and big congregations in parks and pubs. Christmas family reunions are also under threat.
The move follows a conference call between the Prime Minister and police chiefs, who said the law had to be made simpler if their officers were to enforce it.
Police will now be encouraged to step up patrols and break up large groups.
Yesterday Hancock said the recent spike in cases served as a reminder to the nation that the virus "remains a threat".
He stressed that social distancing was the first line of defence and said he was concerned about the situation in France and Spain.
In France the hospitalisation rate has trebled in a month while in Spain it has increased 15-fold since July.
A new public information campaign will also launch on Wednesday to highlight how everyone can help stop the spread of the virus by remembering to wash their hands, cover their face and make space.
"Hands. Face. Space" will run across TV, radio, print, out of home, social and digital display advertising, with a new video being released to show exactly how coronavirus spreads indoors.
With people expected to spend more time inside during the winter, the film – produced with the help of scientific experts – encourages the public to follow simple steps to reduce the risk of infection.
The Police Federation of England and Wales urged the Government to "play its part" through the public information campaign after "so many changes in legislation".
The developments come amid reports that the Government could soon launch a crackdown on young people spreading coronavirus,
The UK reported 30 more Covid-19 deaths on Tuesday - the highest one-day total for six weeks - as ministers warned the nation faces more lockdown misery unless social distancing rules are obeyed.
Johnson and Hancock joined medical experts in delivering a desperate appeal for 20 and 30-somethings to rein in their behaviour, amid growing alarm over a surge in cases.
In a potential sign of things to come for the rest of the country, the Health Secretary announced that pubs in Bolton must shut their doors to stem a flare-up.
With immediate effect, they can only serve takeaway, and are obliged to close between 10pm and 5am.
The prospect of banning gatherings of more than six people, which was mooted by some earlier this week, immediately sparked anger from Tory MPs who pointed out that infection levels remain extremely low.
One former minister told MailOnline it would be "dreadful and disproportionate", an "enormous intrusion into private life" and "rule by directive".
However, the latest daily death total of 30 is considerably higher than the three recorded the day before.
The Government has been fearful hospitalisations will soon begin to rise as a result of rising infections, despite scientists reassuring that most cases are among younger, healthy generations.
Official data shows the surge of new cases over July and August has been driven by those in their teens and 20s while cases in older generations continue to decline.
British hospital admissions have remained stable with just one in 100,000 people currently needing medical care for Covid-19 infection, which further supports people aren't getting seriously sick with the disease.
It follows Hancock telling MPs in the House of Commons that "just because we've come through one peak, it does not mean we cannot see another one coming".
Several locations in the UK have had to impose tighter Covid-19 restrictions to try and curb transmission, with pubs in Bolton the first in England to be ordered back into into lockdown.
The Department of Health's update of 30 Covid-19 deaths on Tuesday covers all settings, including hospitals, care homes and private homes.
Scotland recorded three Covid-19 deaths across all settings earlier in the day - the highest since June 30.
It comes after several weeks with barely any deaths and after First Minister Nicola Sturgeon warned this week hospitalisations may also be on the up.
The vastly increased number of deaths does not appear to be as a result of the 'weekend' or 'bank holiday' effect, when a delay in reporting deaths leads to a higher number on Tuesday, given that trends show three deaths were reported last Tuesday, and only 16 the week before that.
The last time deaths were this high was July 29, when 34 deaths were reported. Daily fatalities have continuously declined since then.
Tuesday's high death count may just be as a result of historical data.
Scientists tend not to put much weight on a singular daily figure and look at trends over time.
It is too early to say what it means, if it is significant. However, it follows a barrage of warnings from Hancock that hospitalisations and deaths would follow a rise in cases over July and August.
Cases have been on an upward trajectory in the late summer, with some 2193 people now being diagnosed each day, on average.
Infection rates are highest among those in their teens and 20s, official data shows, and Hancock has said it is mostly '17 to 21 year olds' testing positive.
Scientists have consistently said this is not something to worry about until spread starts spilling into the vulnerable and elderly parts of the community - which hospital and death data has so far suggested is not the case.
Health officials are rattled, however, and are warning young people to stop going to parties and large gatherings and to respect the social distancing laws.
Hancock yesterday appeared on Radio 1 to tell youngsters 'Don't kill your gran' as deputy chief medical officer Jonathan Van-Tam said people had 'relaxed too much'.
England's chief medical officer, Professor Chris Whitty, has also warned that if people stop social distancing then 'Covid comes back'.
Hancock's warning of a potential second wave in the UK - one of many in recent weeks - comes just a day after he said cases in Britain are not spiralling out of control.
Scientists, too, have said there is nothing unexpected about the uptick in cases, given that so many lockdown restrictions had been eased this summer.
Dr Andrew Preston, a reader in microbial pathogenesis at the University of Bath, told MailOnline: "A rise in infections was inevitable. The way we reduced infections in the first place was though a very draconian lockdown."
However, experts agree there is an element of risk that new cases - predominantly in young people - could lead to hikes in hospitalisations if people are not careful.
But reassuring data shows hospital admissions in Europe are still at only a fraction of the level they were in March and April.
Johnson was last night urged to think very carefully before imposing a new lockdown in response to a spike in virus cases.
Business leaders, MPs and scientists told the Prime Minister to consider other options first, with one think-tank warning a second shutdown would be "catastrophic".
Mike Cherry of the Federation of Small Businesses said the first national lockdown was incredibly damaging, adding: "If we can avoid a second through the utilisation of alternative measures to contain the virus, that would give hope to a lot of small firms as they try to get back on their feet."
Hancock said he would not "shy away from taking targeted local action", such as that imposed yesterday in Bolton.