Carnival Corp's troubled Ruby Princess cruise liner, the biggest single source of coronavirus infections in Australia, docked south of Sydney on Monday to get help for sick crew members requiring urgent medical treatment.

The Ruby Princess, now the target of a criminal investigation led by the homicide squad in the state of New South Wales (NSW), has more than 1,000 crew still on board, after passengers disembarked in mid-March without health checks.

There have been at least 360 COVID-19 cases, including passengers and staff, associated with the vessel, which includes at least six deaths.

As a popular Pacific port destination, Australia is among numerous countries around the world negotiating arrangements with cruise ships unable to find somewhere to dock.

NSW Police said in a statement on Monday that the vessel may remain in place for up to 10 days, but the crew will not disembark unless approved by state authorities.

Sick crew members were being treated on board or transferred to hospital, police said, and the vessel will be refueled in preparation for departure.

Australia has more than 5,700 confirmed COVID-19 cases and its death toll rose to 40 on Monday after five additional deaths were recorded overnight.

An investigation into Ruby Princess protocols will focus on communications and actions that led to the docking and ­disembarking of the ship's 2,700 passengers on March 19 at ­Sydney Harbour to see whether biosecurity laws or state laws were broken, authorities said.

State health authorities had classed the ship as low risk, and the Australian Border Force issued a notice allowing the passengers to travel home freely. They were required to self-­isolate for 14 days.

The ship has remained in Australian waters and on Monday docked at Port Kembla, with the remaining crew from 50 different countries and regions on board to stay in isolation.

The government banned cruise ships from docking except for emergencies as of mid-March and has sent off most of the cruise ships that remained in Australian waters over the past week.

Australia has seen a sharp drop in the rate of new cases after closing national and state borders, quarantining people on all incoming flights in hotels for 14 days, restricting public gatherings to two, and shutting pubs, restaurants and gyms.

While the growth in new cases slows, the number of people contracting the virus from an unknown local source is steadily growing, particularly in NSW.

Australia's Deputy Chief Medical Officer Paul Kelly said 8 percent of coronavirus cases are now locally acquired.