Passengers of luxury liner Diamond Princess who were cleared of the coronavirus began disembarking yesterday, amid growing criticism of how the 14-day quarantine period had been handled.

The first batch of 443 passengers out of the 3,000 or so still on board were allowed to leave the ship. But the Health Ministry also said that another 79 people on board had tested positive for the virus, bringing the total number of cases to 621, out of 3,011 results. Over half the confirmed cases are asymptomatic.

Dr Kentaro Iwata, an infectious diseases expert at Kobe University who was on the ship on Tuesday, was scathing in his criticism of how matters had been handled, describing the liner as a "Covid-19 mill".

In a viral YouTube video on Tuesday night, he said it was completely chaotic, with some medical staff and government officials showing absolutely no regard for health and safety protocols.

"The cruise ship was completely inadequate in terms of infection control. There was no distinction between Green Zones that are free of infection and Red Zones which are potentially contaminated by the virus," he added.

At least two government officials who were on board have tested positive. Dr Iwata has quarantined himself for two weeks.

But the National Institute of Infectious Diseases said yesterday its epidemiological data showed that most infections had occurred before the ship was quarantined on Feb 5. It insisted the quarantine intervention was effective.

But this reassurance appears to hold little weight among foreign governments arranging to bring home their citizens, who will go through another 14-day quarantine.

Japan confirmed another 10 domestic cases yesterday, bringing the total to 84.