A Cambodian health ministry official says 781 passengers off the cruise liner Westerdam have been tested for coronavirus and all tested negative.

Cambodian health officials have conducted tests for the coronavirus on 781 people, including many Australians, who arrived on the cruise ship Westerdam and all have tested negative, a health ministry spokeswoman says.

"We are working on that, the test results, we are waiting for more to come in," the official, who declined to give her name, told AAP on Wednesday.

Seventy-nine Australians were among the 2257 passengers on board the Westerdam when it docked in the southern port of Sihanoukville on Friday, after being denied entry at six ports across East Asia amid fears of a coronavirus outbreak.

Officials said about 500 passengers remain in the capital while others were in Sihanoukville or still aboard the Westerdam.

The government-friendly Khmer Times said the first batch of 130 passengers who arrived in Phnom Penh from Sihanoukville had left for Australia, the US, Europe and Hong Kong.

Others had flown to Singapore, Japan and Thailand with Western embassies co-operating in an effort to secure charter flights.

Holland America Line, owners of the cruise liner, said in a statement that all passengers would be contacted by local health department officials once they returned home.

Most passengers were taken to the Sokha Hotel, isolated on a peninsula which fronts Phnom Penh, however, journalists have been barred from talking with them.

The Khmer Times said reporters who did make contact were taken into an isolated room and were forced to delete their pictures before being allowed to leave.

Meanwhile, Cambodian Prime Minister Hun Sen took a swipe at his critics who accused his government of bringing the virus into the country after an American who travelled on the Westerdam tested positive for the coronavirus in Malaysia.

"But I ask you: Has any Cambodian contracted the virus? Secondly, has a cruise passenger tested positive for the virus while staying in Cambodia? No one," he told a graduation ceremony at a local university.