An Australian cruise ship has been turned away from New Caledonia amid fears of swine flu.

The Dawn Princess cruise liner was prevented from stopping after up to five people on board started showing flu-like symptoms.

Swabs have been taken from the sick passengers and sent to Sydney for testing.

Dr Jeremy McAnulty from New South Wales Health says the ship has not been to any swine flu infected countries but they are still being cautious.

"We've learnt a lot from cruise ships and transmission of diseases over the last few years, but also particularly in the past week or so," he said.

"We're working to identify people who may have had infections on board to help determine whether it was swine flu or something else."

The ship is now heading back to Sydney and will arrive on Friday.

Today the number of confirmed cases of swine flu in Australia has risen to about 500, with Victoria's tally now at 395.

Cruise ships have been in the spotlight since late last month, when about 3,000 passengers and crew on board the Dawn Princess were not allowed to leave the ship in Sydney because four passengers displayed mild flu symptoms.

The passengers and crew were then allowed to disembark but told to remain in home isolation until the all-clear was given.

Then cases of swine flu appeared on the P&O cruise ship Pacific Dawn, which docked in Sydney yesterday.

The 1,800 passengers on the ship were cleared of swine flu and were allowed to disembark, although three crew members were confirmed to have the virus.

Passengers on the ship's previous cruise were found to have swine flu.

Yesterday the chief executive of Carnival Cruises, which runs P&O, said passengers might be screened before they boarded the ship for its next cruise to the South Pacific.