The new coronavirus epidemic swelled on Wednesday with cases in South Korea surging past 1,000 after deaths soared in Iran and infections appeared in previously untouched countries, prompting dire warnings that the world was not ready to contain it.

China reported 52 new coronavirus deaths today — the lowest figure in more than three weeks — bringing the total death toll to 2,762. All the new deaths were in the outbreak epicentre Hubei province, which accounted for 401 of the 406 new infections reported on Wednesday, the National Health Commission said.

The virus has rapidly spread in parts of Asia, Europe and the Middle East, even as the number of deaths and fresh cases decline at the disease epicentre in China.

Towns and cities have been sealed off in an attempt to stop the contagion, while hotels in the Canary Islands and Austria were locked down on Tuesday because of suspected cases.

In Iran, which has reported 15 deaths out of nearly 100 infections, even the country's deputy health minister Iraj Harirchi said he had contracted the virus.

At the World Health Organisation headquarters in Geneva, Bruce Aylward, who headed an international expert mission to China, hailed the drastic quarantine and containment measures taken by the country.

But he told reporters that other nations were "simply not ready" to contain the outbreak.

"You have to be ready to manage this at a larger scale... and it has to be done fast," Aylward said.

The virus has killed 2,715 people and infected over 78,000 in China. There were 52 more deaths reported on Wednesday — the lowest in three weeks — with no fatalities outside the epicentre in central Hubei province.

The National Health Commission also reported a drop in new infections to 406, with only five outside Hubei — a figure that will boost confidence that the rest of the country is containing the epidemic.

In the rest of the world, there have been more than 40 deaths and 2,700 cases.

The disease has now reached dozens of countries, with Austria, Croatia and Switzerland the latest to declare cases.

The epidemic's disruption has also grown, with stock markets tumbling around the world, restrictions imposed on travellers and sporting events cancelled.

The WHO, the UN health agency, has called for countries to "prepare for a potential pandemic" — a term used to describe an epidemic that spreads throughout the world.

Poor countries are particularly at risk, the WHO has warned.

• South Korea surge -

South Korea reported 169 new infections on Wednesday, raising its total tally to 1,146 — by far the largest outside China — while an 11th person died.

The vast majority — 90 per cent — of the new infections were in Daegu, the country's fourth-largest city and the epicentre of the outbreak, and the neighbouring province of North Gyeongsang.

The streets of Daegu — which has a population of 2.5 million — have been largely deserted for days, apart from long queues at the few shops with masks for sale.

Authorities urged the public to exercise extra caution, advising citizens to stay home if they have a fever or respiratory symptoms.

China quarantined 94 air passengers arriving in Nanjing from Seoul after three people, all Chinese, on the flight were discovered to have fevers on Tuesday.

Iran, Italy hotspots

In the Middle East, Iran has emerged as a major hotspot, with three more people dying from the COVID-19 disease on Tuesday.

The country has been scrambling to contain the epidemic since last week when it announced its first two deaths in Qom, a centre for Islamic studies and pilgrims that attracts scholars from abroad.

US Secretary of State Mike Pompeo, whose country came to the brink of war with Iran earlier this year, said Washington is deeply concerned Tehran "may have suppressed vital details" about the outbreak there.

Gulf countries announced new measures to cut links with Iran in an attempt to stop the spread.

Meanwhile Italy — which has reported 10 deaths and more than 300 cases — has locked down 11 towns and ordered Serie A football games to be played to empty stadiums.

A young man who returned to Croatia from Italy became the first case in the Balkans region.

In the United States, which has a few dozen cases, health authorities urged local governments, businesses, and schools to develop plans like cancelling mass gatherings or switching to teleworking as the country braces for the virus to spread further.