The cruise ship, at the centre of a political storm and a criminal investigation over how almost 2700 passengers were allowed to disembark - and go on to infect many nationwide - had docked at berth 104 near the Port Kembla Grain Terminal, with crew confined to quarters.

Defence force members joined the police Marine Area Command efforts to maintain security around the beleaguered vessel from Tuesday.

She has become the largest single source of this coronavirus in NSW, responsible for more than 620 cases - mostly passengers - and 15 deaths.

Read more: Govt dumped its problems on the Illawarra, says Park

Many of the 1400 crew are now exhibiting symptoms.

South Coast Labour Council secretary Arthur Rorris said transport unions had still been denied access to the ship's crew and they held "grave concerns" about their welfare.

"We still have not had access to the ship to verify if crew members are okay," he said.

"So we've written to NSW Health asking them to take control of the ship - we have no confidence in the contractor and have grave concerns about the welfare of our members."

The Port Kembla Mission to Seafarers charity has also ramped up a huge effort to care for the well-being of the ship's staff and crew, organising care packages from across the Illawarra to be given to those stuck on board.

ADF personnel were helping police monitor compliance under new public health laws. Deployments to other ports including Newcastle and Eden are expected later this week.

Meanwhile, Port Kembla's Mission to Seafarers has been organising care packages to the 1400 crew.

"They are distressed, as you can understand," chaplain the Rev John Kewa said.

"Nobody's allowed to go visit them on board the ship. We try to reach out in a different way.

"There's a lot of people from around the community in the Illawarra, from Kiama up to north of Wollongong, we have been bombarded with messages coming in, saying is there anything we can do to help that crew?

"That's something completely contradictory to what we see in the media that anyone who has something to do with the Ruby Princess is unlovable at the moment.

"What I'm getting is people who want to send a message to the crew - it's not your fault; we're thinking of you, we hope everything gets better soon."

Wollongong councillor Leigh Colacino, who has been deeply involved in the efforts to bring cruise ships to Wollongong - in more pleasant circumstances - said the packages were "gifts of friendship".

"We would like to know how the ship appeared in our port - that was a decision made without Wollongong being involved," he said.

"That has to be explained. But that's a separate story. Right now they are feeling very isolated. The wider community wants to [be friendly] with them."

Rev Kewa said people had already been delivering gift boxes to the Mission to Seafarers at Port Kembla.

"We are trying to put a gift box together for every single crew," he said. "It's nothing much but the message that goes with that little gift box is important to the crew that is stuck in quarantine."

An email address has also been set up to send messages of support to the crew - rubycrewletters@gmail.com