Three more cruise ships have left Sydney Harbour overnight following a mass police operation to send vessels affected by the coronavirus crisis home — but the stricken Ruby Princess, which has been linked to 600 cases and 10 deaths, remains off the New South Wales coast.

Key points: NSW Police worked with the five ships to organise food and fuel supplies so they were able to leave

NSW Police worked with the five ships to organise food and fuel supplies so they were able to leave The Ruby Princess cruise ship remains in the waters off Sydney while crew await test results

The Ruby Princess cruise ship remains in the waters off Sydney while crew await test results Ruby Princess has had more than 600 COVID-19 cases and 10 deaths

The Celebrity Solstice, Voyager of the Seas and Ovation of the Seas all departed during the night, following the Spectrum of the Seas and Radiance of the Seas which left on Saturday afternoon.

Dubbed 'Operation Nemesis', police worked with the five ships to equip them with supplies, as well as to transfer crew between the cruise liners.

NSW Police described it as the largest peacetime maritime operation in Sydney's history, and it was completed in about 30 hours to allow the ships to leave Australian waters.

All the ships are operated by Royal Caribbean Cruises, aside from Celebrity Solstice which is run by Celebrity Cruises.

The Celebrity Solstice left Sydney Harbour overnight. ( AAP: Dan Himbrechts )

The Ruby Princess, however, was near Palm Beach on Sydney's northern beaches on Sunday morning before sailing south, while 250 crew members await test results.

The ship has seen more than 600 COVID-19 cases develop among its passengers and 10 deaths following its docking in Sydney Harbour on March 19.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 1 minute 26 seconds 1 m 26 s Five cruise ships have been moved out of Sydney Harbour overnight.

NSW Health authorities yesterday defended the Government's decision to allow the ship to dock at Circular Quay despite knowing about specific reports of ill passengers, saying it was the right call to make given the information at the time.

Stay up-to-date on the coronavirus outbreak Download the ABC News app and subscribe to our range of news alerts for the latest on how the pandemic is impacting the world

A spokesman for Carnival Australia, the Ruby Princess's operator, said there was no further information available about what would happen to the stricken ship and its crew.

"We continue to be in close contact with relevant authorities as the health position for onboard crew continues to improve with a strong health management approach," he said.

The other five ships left after following a 14-day isolation period. All ships returned to their home ports with only crew on board.

The Celebrity Solstice, which had 12 COVID-19 cases among its passengers, has headed to Singapore, as has The Ovation of the Seas (84 cases).

The Voyager of the Seas, which had 34 cases as well as 5 crew members, was bound for Bali.

Last month, the Australian Border Force ordered all cruise ships to leave Australian waters before June 15, warning of penalties of up to five years in jail or a $63,000 fine.