The head of the World Health Organization has urged countries around the world to test every suspected coronavirus case as the number of confirmed infections passed 182,000.

"You cannot fight a fire while blindfolded," WHO chief Tedros Adhanom Ghebreyesus told journalists. "Test, test, test. Test every suspected case."

The virus is spreading rapidly, forcing governments to impose restrictions rarely seen outside wartime -- closing borders, ordering home quarantine and scrapping public events including major sporting fixtures.

Tedros said more cases and deaths have now been reported in the rest of the world than in China, where COVID-19 first emerged in December before crisscrossing the globe.

"This is the defining global health crisis of our time," he told reporters. "Crises like this tend to bring out the best and worst of humanity."

More than 182,260 people have been infected by the coronavirus across the world and 7,165 have died, with cases and deaths outside China overtaking those in the country where the outbreak began, according to a Reuters tally published on Tuesday.

Infections outside China have been reported by 161 countries.

There were continuing signs of improvement in China, with only four new COVID-19 cases recorded in Wuhan -- where the virus was first detected in December -- although imported cases rose.

Europe in lockdown

Governments are scrambling to contain not only the spread of the virus but also the economic fallout, with fears it will catapult the world into recession.

Countries across Europe are on full lockdown, while major US cities have shut bars and restaurants and schools are closing nationwide.

In the latest restrictions in Europe, France imposed a 15-day lockdown on its population while Germany announced border controls, banned gatherings in churches, mosques and synagogues and said playgrounds and non-essential shops would close.

Spain also announced it would seal off its land bordes as the number of cases edged closer to 10,000, while Britain called for an end to all "non-essential" contact and travel, and Switzerland declared a state of emergency.

Italy -- the hardest hit nation in Europe -- announced another surge in deaths, taking its overall toll to more than 2,000.

Iran, the country with the highest number of infections and deaths in the Middle East, closed four key Shiite pilgrimage sites.

'Never seen shopping like this'

In the United States, the US Federal Reserve sought again to shore up the economy, announcing another USD 500 billion in cash injections after slashing its key interest rate to virtually zero.

The Bank of Japan on Monday also announced emergency economic stimulus measures for the world''s third-biggest economy.

But stock markets and oil prices went into freefall again as the various central bank moves failed to lift confidence.

Wall Street stocks sank more than 10 per cent after a brief suspension triggered by steep losses, following sharp nosedives in European markets.

"The biggest concern has to be that the big G7 central banks have exhausted their policy tool kit, especially the biggest and most influential one of them all, the Fed," said AxiCorp''s Stephen Innes.

Major world airlines on Monday axed almost all flights temporarily, triggering pleas to help carriers survive.

China provided more evidence of COVID-19's dire economic impact, announcing factory output had contracted for the first time in nearly 30 years.

There have been scenes of panic-buying around the world as anxious people stock up on essentials fearing a lengthy period of enforced quarantine.

Larry Grossman, manager at a Manhattan supermarket, said he had never seen anything like it in 40 years.

"I have been through Hurricane Sandy... through 9/11, I have never seen shopping like this," he told AFP as he restocked empty shelves.