Around 650 Aust'n hospital patients potentially exposed to hepatitis B

Around 650 patients at an Australian hospital could have been infected by hepatitis B after being treated by a staff member with the disease.

Victoria's Department of Health and Human Services has sent letters to the patients of a Melbourne metropolitan health facility who came into direct contact with the worker, who reportedly has had the disease for the past three years.

The department has requested the group be tested for the form of hepatitis - which can cause abdominal pain, dark urine, fever, joint pain, loss of appetite, nausea and vomiting, weakness and fatigue, and yellowing of the skin and whites of the eyes - in the coming weeks.

Victoria's acting chief health officer Roscoe Taylor, who would not name the hospital or worker in question, said there was less than a one percent chance the patients had been infected, but testing was required.

"This health worker has been carrying out clinical procedures, some of which included exposure-prone procedures," he said in a statement published by Fairfax Media on Thursday.

"These procedures have an increased risk of skin puncture and therefore potential for the transmission of a blood-borne virus."

Fairfax Media reported on Thursday that the staff member made his superiors aware of his diagnosis in late August in 2015.

It is currently unknown how long the worker knew he was hepatitis B-positive before he told his employer, but an investigation is underway.

The letter, which states a specialized team will conduct the testing, has already attracted more than 150 respondents.

Hepatitis B is a sexually transmitted disease, but in rare cases the infectious condition is spread through blood-to-blood incidents.

In 2014, a similar scare took place at a Victorian dentistry, leading to more than 400 patients being tracked down and tested for HIV.