The prime minister has encouraged people who have found themselves isolated overseas to get in contact with the Department of Foreign Affairs and Trade, either directly or through their family.

The department can then consider what consular support and advice they can provide to "help get them home", he said.

DFAT is particularly focusing its attention on areas where large groups are struggling to get home, including Lima in Peru and some cruise ships.

"This is one of the many challenges we are working on," Mr Morrison told reporters in Canberra on Sunday.

"And at this stage, I am not going to advance to the point of suggesting any particular flights. But obviously we are working to solve that problem."

The prime minister said the NSW and federal governments had also doubled down on their commitment to "work together as closely as we can" on matters such as handling cruise ship arrivals.

NSW Health is scrambling to contact thousands of people who were onboard four cruise ships which visited Sydney this month, which carried passengers which were infected with coronavirus.

The Ruby Princess ship was also allowed to dock in Sydney with four people carrying the potentially deadly disease.

In all cases passengers were allowed to disembark without being tested.

"We're going to have lots of challenges," Mr Morrison said.

"All of those who are working on these issues, whether it's those who have to provide the health clearance for those that leave the ship ... or those at border force who have their job as part of this process, they have to work together carefully."

Australian Associated Press