More than 370 legal experts have signed a letter coordinated by the Australian National University and the University of Technology Sydney, which calls for urgent reforms to protect the prison population from the global health pandemic.

"Australian prisons and detention centres will become epicentres for the transmission of COVID-19 if governments don't act now," leader of the ANU criminology program Professor Lorana Bartels said in a statement.

The experts are urging the early release of vulnerable prisoners and detainees who are at high risk of harm from COVID-19, such as those with pre-existing conditions, the elderly and the young.

They also believe those detained for offences such as unlawful driving, property crimes and those who are likely to be released in the next six months should also be freed.

UTS Professor Thalia Anthony said urgent measures, including the release of prisoners, have been undertaken in the US, the UK, southeast Asia and the Middle East in response to the virus.

She said Australian governments must provide a coherent approach to protect prison populations.

"It is only a matter of time before COVID-19 breaks out in prisons and youth detentions centres. This will then have a substantial flow-on effect to the community," she said.

Professor Bartels said most people who enter prison are un-sentenced and nearly a third are expected to serve less than 12 months.

"Tens of thousands of people are likely to be released into the community by the end of the year, making them potential carriers of the coronavirus back into communities," she said.

Justice Action coordinator Brett Collins told AAP earlier this week riots seen in Italy's prisons would be replicated in Australia if authorities couldn't prevent COVID-19 outbreaks.

He also argued older prisoners are at high risk of dying and should be released and that nobody should be sharing cells to ensure proper social distancing.

Australian Associated Press