The Tasmanian government will spend $340 million to build new prison facilities in the state's north and south if re-elected, the premier has promised.

Premier Will Hodgman and Opposition Leader Rebecca White are both out and about as the state prepares to head to the polls.

No date has been announced for an election, but it’s expected to be in March.

The government on Sunday pledged $340 million toward prison infrastructure, including a 270-bed prison in the state’s north and a new remand centre in the south for up to 70 inmates.

The new facilities will keep the community safe and boost the economy, with the creation of more than 4000 jobs, Mr Hodgman says.

“An investment of this scale is only possible because we’ve brought the budget back into balance, so we are able to invest in the infrastructure our state needs,” he said.

Minister for Corrections Elise Archer said the northern prison, to include a women’s prison facility, would also boost rehabilitation prospects because it would be easier for families to visit prisoners from the region.

An internal Liberal Party MediaReach poll of 3000 Tasmanians conducted last week shows the Liberals had 41.1 per cent of the primary vote, Labor had 34.3 per cent and the Greens 12.8 per cent, the Hobart Mercury has reported.

Ms White is set to announce Labor’s housing affordability plan at the launch of the Denison and Franklin candidates.