Thousands of people were stranded aboard two cruise ships in Asia on Thursday, quarantined by officials desperate to stem the spread of a deadly virus that has killed hundreds in China and spread panic worldwide.

At least 20 people on board one ocean liner off the Japanese coast have tested positive for the new coronavirus, with thousands more facing two weeks of isolation.

The outbreak on the vessel, whose 3,700 passengers and crew hail from over 50 countries, is the latest development in a snowballing global health emergency that has left more than 560 people dead, most of them in China.

In Hong Kong, 3,600 people spent the night confined aboard the cruise ship World Dream as authorities conducted health checks after three former passengers tested positive for the virus.

Since emerging from central China in December the virus has killed 563 people and infected over 24,000 more – including a few hundred outside the mainland.

The World Health Organisation, which has declared the outbreak a global health emergency, on Wednesday appealed for $675 million to fight the virus.

In Japan, more than 3,700 your staterooms as we are negotiating with the Japanese quarantine officials to allow small groups of guests to spend some time on the open decks to get some fresh air.”

British passenger David Abel uploaded a series of videos on his Facebook page, jokingly asking the captain to send him some whisky and requesting a banana a day from room service.

“It’s a horrible situation for most passengers onboard, being stuck here, confined to the cabin,” he said, sympathising especially with those with inside rooms.

“It must be almost unbearable for them.”

City health officials in Hong Kong said passengers would only be allowed off the World Dream after tests were completed, with crew checked first and passengers to be screened on Thursday.

Panic buyers in the city descended on supermarkets to snap up toilet rolls as the government warned that online rumours of shortages were hampering the city’s fight against the virus.

On Wednesday, city authorities announced anyone arriving from the Chinese mainland from Saturday would face a mandatory two-week quarantine.

Two dozen countries now have confirmed cases of the novel coronavirus that emerged from a Wuhan market selling exotic animals at the end of last year.

China is struggling with a shortage of hospital beds, equipment and materials to treat those infected, despite building two hospitals from scratch and converting public buildings to house patients.