TOKYO (Reuters) - Japan plans to start trials of HIV medications to treat coronavirus patients as an increase in the number of cases poses a growing threat to the economy and public health, the government’s top spokesman said on Tuesday.

The government is making “preparations so that clinical trials using HIV medication on the novel coronavirus can start as soon as possible,” Yoshihide Suga told a briefing, but added he could not say how long it might take to approve a drug’s use.

A further 88 people tested positive for the virus on the Diamond Princess cruise ship quarantined off the port of Yokohama, bringing the total number of infected passengers to 542, the Health Ministry said.

Elsewhere, three more cases were diagnosed in Wakayama Prefecture, including the son of a doctor infected with the virus, local media said.

As the contracting economy deepens recession fears, the spread of the virus has prompted Tokyo to curb the size of public gatherings, while some companies are telling employees to work from home.

HIV drugs have been touted as a potential cure for the coronavirus, which has killed almost 1,900 people in mainland China. No therapy has yet proven fully effective against the infection.

People in China have begun exploring unorthodox ways to get treated, with some appealing to HIV patients and unauthorised importers for medicine.

In Thailand, doctors said they appeared to have had some success in treating severe cases of the virus with a combination of medications for flu and HIV.

As demand for surgical masks surges in Japan, police were investigating the theft of 6,000 masks reported by the Kobe Red Cross Hospital in the central city, a hospital official said.

FILE PHOTO: Passengers wearing protective face masks are seen on the cruise ship Diamond Princess, as the vessel's passengers continue to be tested for coronavirus, at Daikoku Pier Cruise Terminal in Yokohama, south of Tokyo, Japan February 16, 2020. REUTERS/Athit Perawongmetha

Japanese officials have promised to work hard to avoid disruption to the Olympic Games starting in Tokyo in July, but concern about the virus led Mongolia’s Olympics archery team to cancel training in Japan, the Kyodo news agency said.

DIAMOND PRINCESS EVACUATIONS

U.S. government evacuation flights on Monday flew home more than 300 Americans who had been on board the Diamond Princess.

With more than 3,000 passengers and crew, the ship has been in quarantine since early this month, after a passenger who had left it in Hong Kong was diagnosed with the virus.

The vessel will receive meals from World Central Kitchen, a non-profit set up by celebrity chef Jose Andres, in a bid to reduce the burden on crew, said Rai Caluori, vice president of vessel operator Princess Cruises.

Passengers still on the ship, about half of whom are Japanese, have expressed frustration over the quarantine and authorities in Australia, Canada, Italy and South Korea are also planning to evacuate citizens from the cruise liner.

A plane chartered by the Canadian government has left for Japan to evacuate its nationals, TV Asahi said. Canada has said 14 days of quarantine await them on their return.

South Korea is also sending a government charter flight on Tuesday to take home four citizens, and a Japanese spouse, who have no symptoms, a South Korean official said.

Japanese who test negative will begin disembarking as early as Wednesday, Health Minister Katsunobu Kato said.

“Everyone wants to return home as soon as possible, so considering that feeling, we are making preparations,” Kato told reporters.

Disembarkation was set for Feb. 19 to 21, Japan’s vice health minister said, according to a copy of a letter circulated on Twitter by a passenger using the handle @daxa–tw. The letter said local health authorities would take passengers’ temperatures before they left the ship.