An Australian infectious disease expert is in Japan to help authorities cope with concerns for passengers aboard the Diamond Princess cruise ship quarantined in Yokohama due to coronavirus.

The expert joins an international team to gather information about the passengers, including the 200 Australians aboard.

The US is sending an aircraft to Japan to bring back US passengers on the Diamond Princess, where the most coronavirus infections outside China have occurred.

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The Australian Embassy in Tokyo emailed citizens aboard the cruise ship to say the federal government is also examining options to assist Australians.

The federal government last week extended the two-week travel ban from mainland China for another seven days to prevent the spread of the COVID-19.

The Australian Chamber of Commerce and Industry states it's "absolutely paramount" to keep citizens safe from the virus, but it is a "savage blow" to

the nation's tourism.

"Tourism and trade would greatly benefit from even a partial lifting of the ban from provinces in China that present a much lower risk to Australians," Australian Chamber Tourism Executive chair John Hart wrote.

The Maritime Union of Australia is concerned its members are at risk by the arrival of container vessels from mainland China, which it says in some cases are docking in breach of the travel ban.

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Opposition Leader Anthony Albanese raised the issue with the government and the chief medical officer, and has been assured they are aware of the situation.

No quarantined Australians at Christmas Island and Darwin have tested positive for the virus and the first group of evacuees are due to return home on Monday.

Of the 15 coronavirus cases in Australia, six have been cleared and the remaining nine are all stable.

In China, the total number of people infected by the virus rose to more than 66,000 on Saturday, with the number of deaths passing 1500.