Also, a trade unionist who has spoken to several of the crew on board has said only around 7 per cent of the 1200 crew have been tested for coronavirus.

The cruise ship arrived in Port Kembla on Monday morning for 10 days, and is docked at berth 104 near the grain terminal with crew confined to quarters.

Heavily guarded by police and defence force, the Ruby Princess is the largest single source of coronavirus in NSW and is responsible for more than 620 cases - mostly passengers - and 15 deaths nationwide.

On Thursday morning NSW Police Commissioner Mick Fuller told reporters that around three-quarters of the more than 1000 crew members had indicated they wanted to remain on the ship, that they felt safe.

However, Dean Summers, national co-ordinator for the International Transport Workers Federation (ITF), said he had spoken to crew who did not feel that way at all.

"The crew are pretty pissed off about Mick Fuller's claims that 75 per cent of them want to stay there, because no-one was asked," Mr Summers said.

"Maybe he got that from the company HR, but that's not the way people feel on board."

While there were as many as 1200 people on board, Mr Summers said the Aspen medical team had tested only around 7 per cent - those with the most obvious symptoms.

"Aspen has sent 10 agents on board and tested the 88 people who were sick," he said.

READ MORE: Waiting for Princess to give them a call

"These 88 people had chronic respiratory problems. They've been tested and now we are demanding the response, we want to know who is sick and who's not sick on board."

He also claimed crew had asked to be tested but had been refused.

"The prisoners in Long Bay, if they were sick they'd be treated for COVID-19 under these circumstances," he said.

"That's not happening here."

On Wednesday night, NSW Police raided the ship, seizing the ship's black box as part of a criminal investigation.

Specialist detectives from Strike Force Bast boarded the ship around 7pm as part of the investigation into the disembarking of the vessel in Sydney on March 19.

Because of the investigation, NSW Health would not state how many people suffering from COVID-19 had been taken off the ship.

Results of the 88 crew members tested was expected to be completed on Friday.

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