Britain ordered a three-week lockdown on Monday in a bid to slow the spread of coronavirus as world health officials warned that the pandemic was "accelerating" around the globe.

As Britain joined other nations in imposing strict stay-at-home orders, the number of virus deaths worldwide surged past 16 500 and the number of confirmed cases surpassed 378 000.

The death toll in New York City neared 100, sparking growing concern over the spread of the virus in the largest US metropolis, home to some 8.4 million people.

UN Secretary-General Antonio Guterres appealed for an immediate ceasefire in the world's conflict zones, and France and China called for urgent talks of the G20 major economies to respond to the escalating crisis.

In Washington, congressional efforts to pass a nearly two-trillion-dollar rescue package for the teetering US economy failed for a second straight day after Democrats said the Republican proposal prioritises big corporations and insufficiently protects workers.

Markets on both sides of the Atlantic were hammered again as the virus continued to wreak havoc on the world economy, spurring fears of a global fallout not seen since the Great Depression.

And with major cultural and sporting events already wiped off the calendar, there were mounting calls to postpone the Tokyo Olympics. Japan's prime minister admitted a delay could be "inevitable".

'Stay at home'

In London, British Prime Minister Boris Johnson ordered a three-week shutdown of "non-essential" shops and services and banned gatherings of more than two people.

"Stay at home", Johnson said in a televised address to the nation, as he unveiled unprecedented peacetime measures after the country's death toll climbed to 335.

The announcement came after crowds of people were seen enjoying weekend spring sunshine in parks and countryside across the country, prompting calls for tougher action to be imposed.

World Health Organisation chief Tedros Adhanom Ghebreyesus warned that the global pandemic was clearly "accelerating".

The number of coronavirus deaths surged past 16 100 on Monday, with over 361 500 infections in over 174 countries and territories, according to an AFP tally based on official sources.

Tedros said it took 67 days from the beginning of the outbreak in China in December for the virus to infect the first 100 000 people worldwide.

In comparison, it took 11 days for the second 100 000 cases and just four days for the third 100 000 cases, he said.

Tedros acknowledged that a number of countries were struggling to take more aggressive measures because of a lack of resources but said "we are not helpless bystanders.

"We can change the trajectory of this pandemic," he said.

Over 10 000 deaths in Europe

More than 10 000 people have now died in Europe alone, the new epicenter of the disease.

The countries that have recorded the most deaths over the last 24 hours are Italy, with 601, Spain with 462 and France with 186.

Italy, with 6 077 deaths, now has more fatalities than China but the number of single-day deaths was slightly down on Monday, offering a glimmer of hope it may finally be turning a corner.

The number of new declared infections in Italy fell from 6 557 on Saturday to 4 789 on Monday.

There have been 573 deaths in the United States - 98 of them in New York City alone, which has become the epicenter of America's coronavirus crisis.

Millions of residents have been ordered to stay at home in the Big Apple and all non-essential businesses have been shut and schools closed.

As only non-essential workers, such as pharmacists, grocery store workers and nurses and doctors, headed to work on Monday, rush hour in the city was just a trickle of traffic.

But President Donald Trump - who faces reelection in November and is keen to avoid extended economic damage in the US - told reporters he would soon be "opening up our country to business because our country was meant to be open".

At least 1.7 billion people globally have now been asked to stay home in line with mandatory or recommended measures, according to an AFP count.

New Zealand and South Africa announced new lockdowns, Germany banned even small gatherings, Italy barred domestic travel and Hong Kong shut its borders to non-residents.

Other European nations continued to choke people's movement, with Britain and Greece the latest to follow Italy, Spain and France in imposing a nationwide lockdown.

'Folly of war'

France is to tighten its lockdown, strictly limiting physical exercise and closing most open-air markets, Prime Minister Edouard Philippe said on Monday.

The Netherlands is extending a ban on all public gatherings from 6 April until 1 June to curb the spread of the virus.

A frustrated Prime Minister Justin Trudeau told Canadians to stop flouting public health recommendations and to self-isolate. "Enough is enough," Trudeau said. "Go home and stay home."

South Africa announced a three-week lockdown "to avoid a human catastrophe" with soldiers patrolling the streets to ensure compliance.

Spain readied to extend its state of emergency, which bars people from leaving home unless absolutely essential, until 11 April.

It reported another spike in fatalities, bringing its total to 2 182 dead - the third highest in the world after Italy and China.

With war-ravaged Syria announcing its first coronavirus case, UN chief Guterres appealed for a worldwide ceasefire to protect the vulnerable in conflict zones.

"The fury of the virus illustrates the folly of war," he said.

IMF chief Kristalina Georgieva said the fund stands "ready to deploy all our $1 trillion lending capacity" and warned that the recession could be at least as bad as during the global financial crisis.

As the pandemic overwhelms hospitals, doctors are having to prioritise patients based on their chances of survival.

"We go into medicine to heal people. Not to make choices about who can live," said Philippe Devos, an anaesthesiologist in Belgium.