The Victorian government is set to continue diverting international flights away from Melbourne while it responds to the coronavirus outbreak there, and other states have either refused to take extra travellers or limited the number of people allowed in hotel quarantine at any time.

In an update to the Department of Foreign Affairs and Trade's Smartraveller website, Australians are warned they may need to make new plans.

"Australian states and territories are working to manage the pressure on quarantine facilities for returning Australian citizens and permanent residents," the update on Tuesday said.

"Measures vary from state to state, but include caps on the number of international passenger arrivals and the requirement to contribute to the cost of quarantine."

The federal government has capped arrivals at Sydney airport at 450 people per day and a maximum of 50 per flight.

"Your flight into Australia may be affected. If you're scheduled to fly into Australia in the coming days and weeks, confirm your itinerary and onward travel plans with your airline or travel agent."

The department has told Australians to be ready for their plans to change as they make their way home.

"The situation is changing often and at short notice. Be prepared to make alternative plans."

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Like Australia, New Zealand requires citizens to quarantine in hotels for 14 days upon their arrival in the country, but the government there has moved to ration the number of Kiwis returning home due to the strain on facilities.

New Zealand has limited the number of places available on Air New Zealand flights for international arrivals, and a ban on new bookings had been put in place.

"Air New Zealand has agreed to put a temporary hold on new bookings in the short term, as well as looking at aligning daily arrivals with the capacity available at managed isolation facilities," Housing Minister Megan Woods said.

"People who have already booked flights with Air New Zealand will still be able to enter New Zealand subject to availability of quarantine space."

The Department of Foreign Affairs and Trade has also issued new guidance about travelling to China, telling Australians they may be at risk of arbitrary detention if they ignore government warnings and travel to China.

The Department of Foreign Affairs has updated its travel advice for China on Tuesday to note that "authorities have detained foreigners because they're 'endangering national security'" and Australians may be at risk.

There is a travel ban in place preventing all Australians from going overseas because of the coronavirus pandemic.