Australian coronavirus victims had tested negative in Japan

Two Australians evacuated from the Diamond Princess cruise ship have tested positive for coronavirus on their return home, despite being cleared in Japan, authorities said Friday.

"We have two people who are positive for the COVID-19 virus. Those two people have mild illness," said Dianne Stephens, acting chief health officer for the Northern Territories.

Health officials in Canberra told AFP all 164 Australians who returned home earlier this week "were tested for COVID-19 in Japan and returned negative results".

A total of six Australian evacuees have now been retested and the two -- described as "an older person" and "a younger person" -- tested positive.

The Australian officials stressed that the development of some positive cases among cleared evacuees was "not unexpected", given the continued spread of the disease onboard after testing began.

Hundreds of people have been allowed to leave the ship after being cleared of having the virus, and many have returned to their home countries to face further quarantine.

Hundreds more Japanese passengers were also cleared and warned only to "stay at home unless absolutely necessary," to "never use public" transport and use a mask if they do venture out.

Australia's Chief Medical Officer Professor Brendan Murphy said the public should not be concerned.

"I just want to reassure the community that whilst this is another two cases in Australia, it's a first for some time now. These were expected and we're well-placed to manage them," he said.

Fifteen previous cases of coronavirus in Australia had been linked to the outbreak of the illness in China.

Murphy also expressed confidence that Japan and South Korea -- where the number of infections nearly doubled Thursday to 104 -- would be able to contain the disease.

"Both Japan and South Korea have well-developed health systems. And I would certainly be confident that they will be onto identifying those cases and tracing contacts," he said.

"But it is obviously a concern that any country where there is significant further transmission.