Strict new curbs on life in the UK to tackle the spread of coronavirus have been announced by the prime minister.

From this evening people must stay at home except for shopping for basic necessities, daily exercise, any medical need and travelling to and from essential work.

Shops selling non-essential goods are being told to shut and gatherings in public of more than two people who do not live together are to be prohibited.

The UK death toll has reached 335.

If people do not follow the rules police will have the powers to enforce them, including through fines and dispersing gatherings, Boris Johnson said in a televised statement from Downing Street.

Other premises including libraries, playgrounds and outdoor gyms, and places of worship must also close immediately.

Parks will remain open for exercise but gatherings will be dispersed.

The government is also stopping all social events, including weddings, baptisms and other ceremonies - but funerals will be allowed.

Mr Johnson said the restrictions would be kept under constant review.

"We will look again in three weeks, and relax them if the evidence shows we are able to," he added.

Martin Hewitt, chair of the National Police Chiefs' Council, said the new restrictions were "sensible".

"The majority of people are already making real sacrifices to save lives and we urge everyone to follow the advice that is designed to keep us all safe," he said.

"We are working with the government and other agencies to consider how these new rules can be most effectively enforced."

But Ken Marsh, chairman of the Metropolitan Police Federation, said he was already seeing "large amounts of sickness" among officers across London and enforcing the new restrictions would be "a real, real challenge".

"We will be dealing with it, but I'm not sure we will have the resources to be able to see it through," he added.

Home Secretary Priti Patel said in a tweet: "I know that the coming weeks will be testing for our front-line police officers.

"I will do everything I can to ensure that they have the resources they need to keep themselves and the public safe."

Scotland's First Minister Nicola Sturgeon said the new restrictions "amount to a lockdown" and are "not done lightly".

"I am not going to sugarcoat it in any way," she said. "Coronavirus is the biggest challenge of our lifetime."

In a tweet, First Minister of Northern Ireland Arlene Foster urged people to follow the restrictions "to save lives and protect our hospitals".

First Minister of Wales Mark Drakeford said "these are really big changes for us all".

"We are making them because of the speed the virus is continuing to spread," he added.

Labour leader Jeremy Corbyn said the measures were "the right response".

"There now needs to be clear guidance to employers and workers about which workplaces should close - and the government must close the loopholes to give security to all workers, including the self-employed, as well as renters and mortgage holders," he added.

The prime minister said the measures were necessary to tackle "the biggest threat this country has faced for decades".

"Without a huge national effort to halt the growth of this virus, there will come a moment when no health service in the world could possibly cope; because there won't be enough ventilators, enough intensive care beds, enough doctors and nurses," he said.

"And as we have seen elsewhere, in other countries that also have fantastic health care systems, that is the moment of real danger.

"To put it simply, if too many people become seriously unwell at one time, the NHS will be unable to handle it - meaning more people are likely to die, not just from coronavirus but from other illnesses as well."