The death toll from the novel coronavirus outbreak soared to 722 in China on Saturday, including the first foreign victim, as Hong Kong imposed a mandatory quarantine on mainland arrivals to block the spread of an epidemic that has caused global panic.

With 86 more people dying in mainland China - the highest one-day jump so far - the toll was closing in on the 774 killed worldwide during the 2002-2003 SARS epidemic. A 60-year-old US citizen diagnosed with the virus died on Thursday in Wuhan, the city at the epicentre of the health emergency, according to the US embassy, which did not provide more details about the person.

China's foreign ministry said in a statement to AFP that the victim was a US citizen of Chinese origin. A Japanese man in his 60s with a suspected coronavirus infection also died in hospital in Wuhan, the Japanese foreign ministry said, adding that it was "difficult" to confirm if he had the illness.

The only fatalities outside the mainland were a Chinese man in the Philippines and a 39-year-old man in Hong Kong.

Nearly 35,000 people have been infected by the new strain, which is believed to have emerged in a market selling wild animals in Wuhan last year before spreading across China. The epidemic has prompted the government to lock down cities home to tens of millions of people, as anger mounts over its handling of the crisis, especially after a whistleblowing doctor fell victim to the virus.

Vice Premier Sun Chunlan, on a visit to quarantined Wuhan this week, instructed officials to take a "wartime" approach as they implement drastic measures that include combing the city for feverish residents.

With panic spiralling around the globe - more than 320 cases have emerged in nearly 30 other countries - researchers are racing to find treatments and a vaccine to fight the virus.

While the World Health Organization is set to give the disease a name within days, China's National Health Commission said it would temporarily call it "novel coronavirus pneumonia," or NCP.

Hong Kong began enforcing a two-week quarantine for anyone arriving from mainland China, under threat of both fines and jail terms. Most people will be able to be quarantined at home or in hotels but they will face daily phone calls and spot checks.

The financial hub has 25 confirmed cases with one patient who died earlier this week. The virus has revived memories of the SARS outbreak that killed 299 in the semi-autonomous city, leaving profound psychological scars and saddling residents with a deep distrust of authorities in Beijing who initially covered up the outbreak.

In the last week, Hong Kong has been hit by a wave of panic-buying with supermarket shelves frequently emptied of staple goods such as toilet paper, hand sanitiser, rice and pasta.

Similar scenes were seen in Singapore on Saturday as shoppers cleared grocery store shelves after the city-state, which has 33 confirmed cases, raised its alert level over the virus. China has expanded its own measures far from the epicentre, with cities hundreds of kilometres from Hubei telling residents that only one person per household can leave the house every two days to buy supplies.

On Saturday, Shanghai became the latest jurisdiction to order residents to wear masks in public places, warning that those who don't cooperate will be "seriously" dealt with according to the law.

Anger over the government's handling of the health emergency erupted on social media on Friday after the death of a Wuhan doctor who was silenced by police after he had raised the alarm about the emerging virus threat in December.

The government responded by sending its anti-graft body to Wuhan to launch an investigation after the death of Li Wenliang, an ophthalmologist who contracted the disease while treating a patient.

Other governments around the world have hardened their defences, with several countries banning arrivals from China while major airlines have suspended flights.

New cases emerged abroad, with five British nationals, including a child, testing positive for the virus after staying at the same ski chalet in France.

Asian cruise ships have become a focal point.

Sixty-four people on board the Diamond Princess off Japan's coast have tested positive and passengers aboard the ship have been asked to stay inside their cabins to prevent new infections.