The jab is available for free at state government-run clinics but, unlike many mainland jurisdictions, still costs at GPs and pharmacies for people outside higher risk groups.

Premier and Health Minister Jeremy Rockliff said the expansion, to begin on June 4, was aimed at improving a low rate of vaccination in the age group.

More than 184,000 flu vaccinations have been delivered this year in Tasmania, with two-thirds of the state's over-65 population receiving the jab, above the 60 per cent national average.

"However, we are concerned that only 12.5 per cent of our vulnerable six-month to five-year-olds have been vaccinated, a trend that is also being reported nationwide," Mr Rockliff said.

"It is very important, with the tripling of influenza cases experienced in mainland states, that over the coming eight weeks we target vaccination for our youngest Tasmanians, many of whom have not experienced a winter flu season before."

People in higher risk groups, including those over 65, pregnant women, children aged between six months and five years and Indigenous Tasmanians, are eligible for free flu vaccinations at GPs and pharmacies.

The state-run clinics are slated to run over the next four weeks in major centres and rural locations.

Victoria on Tuesday announced a $33 million free vaccination program involving more than 3000 GPs and community pharmacies.

Australian Associated Press