More than 30 per cent of hepatitis B sufferers in Australians are believed to be living undiagnosed with the potentially fatal ailment.

The Australian Hepatitis Council (AHC) revealed the new data in a bid to raise awareness of the liver virus as part of World Hepatitis Awareness Day this Sunday.

The council believes hepatitis B affects nearly 90,000 Australians, but more than 30 per cent of those people have not being diagnosed due to a lack of awareness of the virus.

"Hepatitis B is a serious health issue that needs greater awareness to break down the longstanding stigmas associated with the disease," AHC chief executive officer Helen Tyrrell said.

Ms Tyrrell said she welcomed the federal government's decision to list hepatitis drug Pegasys (Pegasys) on the Pharmaceutical Benefits Scheme (PBS).

"Given the high incidence and alarmingly low rate of diagnosis and treatment, we believe easier access to therapy via the PBS will encourage more effective management and better diagnosis of hepatitis B," Ms Tyrrell said.

Hepatitis B is caused by a virus that attacks the liver and can cause lifelong infection, cirrhosis of the liver, cancer and even death.

- AAP