Extra funding to the state's fire service is welcome, but not enough to cover budget shortfalls, Tasmanian firefighters say.

The Tasmanian Fire Service (TFS) has absorbed the State Emergency Service (SES) - taking over responsibility from Tasmania Police.

The United Firefighters Union said this will cost the fire service $5 million over two years.

Firefighters have held a rally at Parliament House in Hobart over concerns the Government has not provided enough funding to allow the fire service to operate the SES.

They believe moving control of the SES to the fire service is, in effect, a budget cut to both agencies and they are calling for a budget boost of $2.5 million a year to compensate.

After a meeting with the union on Monday, Emergency Services Minister Rene Hidding pledged $1.5 million in additional funding.

"It is important to note that no frontline firefighters have been cut since we came into office in March last year and, in fact, TFS numbers have increased and will increase further with nine new recruits to commence in coming weeks," the Minister said in a statement.

The union's Tasmanian secretary, Greg Cooper, welcomed the funding but said it fell short of what was needed.

"It's a good initiative and we support it, but it's only one part ... the $5 million is money the fire service has to find that it can't raise," he said.

"It cannot raise funds for other than fire service activities and the Government has not established an independent funding model for that transfer, from police to fire."

The union said the TFS had hoped to build seven new fire trucks this year, but could not cover the cost.

"We need to have a sustainable model, and it needs to be developed fairly quickly."

Mr Hidding said the Government would work "constructively" with the union on a sustainable funding model.

The rally included about 40 firefighters who wore their uniforms, in a direct breach of a management directive not to.