ROME: Italy imposed unprecedented national restrictions on its 60 million people Tuesday over the deadly coronavirus that US President Donald Trump said had "blindsided the world".
The outbreak, combined with a crash in oil prices, has caused carnage on financial markets, erasing billions of dollars globally.
The World Health Organization warned there is a "very real" threat of a pandemic, but its chief said the planet was "not at the mercy" of an illness that has killed more than 4,000 people so far.
In China, where the virus emerged, the outbreak appeared to be coming under control, with authorities announcing just 17 deaths on Tuesday and the lowest number of new infections since reporting began in late January.
But elsewhere, Covid-19 has been spreading rapidly, particularly in Italy, where more than 9,000 cases and 463 deaths have been reported.
In a desperate bid to stem the spread, Italy's Prime Minister Giuseppe Conte went on television to announce the entire country would effectively be placed on lockdown from Tuesday.
"I am going to sign a decree that can be summarised as follows: I stay at home," Conte said.
"Travel must be avoided across the entire peninsula unless it is justified by professional reasons, by cases of need or for health reasons," he told Italians.
'Blindsided the world'
The measures extend a quarantine zone that Italy had imposed for its industrial northern heartland around Milan and Venice on Sunday.
The national restrictions will run until April 3 and mean that schools and universities will all immediately close.
Serie A football matches and all other sporting events are also being suspended for the coming month.
But it was not immediately clear how the measures would be enforced.
Trains and numerous flights continued to operate into and out of Milan on Monday despite the earlier set of restrictions for its Lombardy region.
Since Covid-19 first emerged in China late last year, Italy has become Europe's hardest-hit country.
An AFP count showed the country had recorded more than half of the 862 deaths reported outside China as of Monday night.
Worldwide more than 110,000 cases have been recorded in over 100 countries.
It has disrupted global travel, cancelled sporting events and sent markets into meltdown.
In Washington, President Donald Trump said he would propose "very substantial" economic measures to Congress on Tuesday, adding that the coronavirus has "blindsided the world."
However, some epidemiologists have accused the White House of a strategy concerned more with the political narrative than domestic readiness.
Chief among the complaints has been the lack of testing caused by the Centers for Disease Control and Prevention (CDC) developing its own flawed kits.
Uncertainty over the spread of the virus, coupled with a collapse in oil prices, created panic on the markets during what some dubbed "Black Monday," with the Dow Jones index losing more than 2,000 points.
There were signs of a slight recovery on Tuesday morning trade in Asia, with oil making back some of its losses.
Pandemic threat 'very real': WHO
The run on stock market prices has robbed Trump of one of his main talking points ahead of the November presidential election.
And there was further alarm after at least two Republican lawmakers who recently met with the president announced they were going into self-quarantine, fearing that they were exposed to the virus at a conservative conference.
There are concerns that the United States could become another hotspot for the virus, with at least 26 deaths and 605 confirmed infections so far.
On Monday, passengers were taken ashore from a cruise ship docked in California after at least 21 people on board were diagnosed with the virus.
WHO chief Tedros Adhanom Ghebreyesus has warned that "the threat of a pandemic has become very real."
But he told reporters Monday that "even if we call it a pandemic, still we can contain it and control it.
"It would be the first pandemic in history that can be controlled," he said. "We are not at the mercy of the virus."
He said China appeared to be bringing the epidemic under control, but warned that "the disease has not run its course."