The death toll from China's coronavirus outbreak soared to 722 on Saturday 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.

Nearly 35,000 people have been infected by the new strain, which is believed to have emerged in a market selling wild animals in the central city of 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 were racing to find treatments and a vaccine to fight the virus.

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 city has been on edge as the virus has revived memories of the SARS outbreak that killed 299 in the semi-autonomous city.

City officials hope the new measures will virtually halt the flow of people across the border while allowing the financial hub to remain stocked with food and goods from the mainland.

The SARS epidemic left profound psychological scars and saddled 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.

The government has blamed unfounded rumours of shortages.