At least six people are dead and 28 remain missing after a hotel being used as a coronavirus quarantine facility in the Chinese city of Quanzhou collapsed on Saturday.

Rescue workers are still searching the rubble of the five-storey Xinjia Hotel in the southern province of Fujian.

Seventy-one people were in the building when it collapsed and dozens have been rescued, authorities say.

It is not clear what caused the collapse on Saturday evening.

State media say the hotel was being used as a quarantine facility monitoring people who had had close contact with coronavirus patients. It's reported 58 of the 71 people in the building were under quarantine.

The building's first floor had been undergoing renovation since before the Lunar New Year, the official Xinhua news agency said, adding that police had summoned the building's owner.

The hotel reportedly opened in 2018 and had 80 guest rooms.

The city of Quanzhou has recorded 47 cases of the virus, which first emerged in the city of Wuhan, about 1,000km away.

One woman told the Beijing News website that relatives including her sister had been under quarantine there.

"I can't contact them, they're not answering their phones," she said.

"I'm under quarantine too [at another hotel] and I'm very worried, I don't know what to do. They were healthy, they took their temperatures every day, and the tests showed that everything was normal."

As of Friday, Fujian province had 296 confirmed cases of coronavirus. Meanwhile 10,819 people have been placed under observation because they have been in close contact with someone infected.

The number of new reported cases in China dropped on Saturday to 44, down from 99 the previous day.

The World Health Organization says more than 101,000 people worldwide have now contracted the virus. More than 80,000 of them are in China.

About 3,500 people have died - the majority in the Chinese province of Hubei where the outbreak originated.