Smoked salmon believed to be from Tasmania is the likely cause of two fatal listeriosis cases in New South Wales and Victoria.

Two elderly people in NSW and Victoria have died after contracting listeriosis believed to be linked to smoked salmon from Tasmania.

The Australian Department of Health is also investigating a non-fatal Queensland case of the infection, which is caused by listeria bacteria.

Smoked salmon was the likely cause of the three cases, which occurred between February and June in people aged over 70, the department said on Wednesday.

The pair who died also had "significant underlying health conditions".

Tasmania's Primary Industries Minister Guy Barnett said salmon products from the state were linked to the listeria cases.

"The evidence that I've been provided from the department is that apparently that is the case," he said.

The state's three biggest salmon producers, which are Tassal, Huon Aquaculture and Petuna, have been cleared of any food safety breaches after an investigation by the state primary industries department.

"The three major producers all have appropriate food safety programs in place specific to the seafood industry. This includes listeria management," department chief inspector of primary produce safety Chris Lyall said.

In a statement, Tassal said it was not aware of any evidence linking their companies to the infections.

A Huon Aquaculture statement said the company's cold smoked salmon products were recently tested by health authorities and no positive results for listeria were recorded.

Several people died in NSW and Victoria last year after an outbreak of listeria in rockmelons.

The bacteria can grow in refrigeration systems and produces mild symptoms in healthy people but can be deadly to those with lowered immune systems.

"This is a timely reminder for people to ensure that food is handled, prepared and stored safely, and that those most at-risk of listeriosis avoid certain foods," the federal health department said.

Foods that have a higher risk of contamination include chilled seafood, cold meats, cold cooked chicken and pre-packaged fruit or vegetable salads.

Those at increased risk include pregnant women and their unborn babies, newborn babies and the elderly.

Symptoms are flu-like, such as fever, chills, muscle aches and nausea.