Tasmania's Premier has made a special request for the Federal Government to foot the bill for the fires burning in the state's world heritage area.

Key points: Will Hodgman says the Commonwealth's contribution to fighting fires would not likely cover world heritage areas

Will Hodgman says the Commonwealth's contribution to fighting fires would not likely cover world heritage areas The Premier and Prime Minister met on a visit to the Huon Valley recently

The Premier and Prime Minister met on a visit to the Huon Valley recently Bushfires have now burnt through 200,000 hectares and the damage bill is likely to keep rising

Bushfires ignited by dry lighting have been burning since December.

Tens of thousands of hectares have been burnt across three large fires affecting the Tasmanian Wilderness World Heritage Area (TWHHA).

The Tasmanian Government is still assessing the cost of the blazes still raging across the state, but the final figure is likely to be in the tens of millions of dollars.

Premier Will Hodgman has confirmed that he wrote to Prime Minister Scott Morrison on January 25 to make a special request outside of the disaster relief scheme for the TWWHA firefighting effort.

The Riveaux Road fire has affected wilderness areas near Federation Peak. ( Supplied: Mark Holdsworth )

Under the Commonwealth's National Disaster Relief and Recovery Arrangements (NDRRA), the Federal Government covers up to 75 per cent of the damage bill but it only applies to people, public assets, some business grants and the clean-up.

Mr Hodgman said the Commonwealth contribution to the fires would be significant, but it would not cover the firefighting efforts in the TWHAA.

"We've got a large part of our state that is world heritage listed," he said.

"It's an asset, but importantly it's also something that we need to protect in massive fire events such as this and that does come at a cost as well.

The grey areas show the extent of damage from bushfires raging through Tasmania's south-west wilderness areas. ( Supplied: TasALERT )

"I've written to the Prime Minister some time ago to express my concerns that those costs may not be met under the National Disaster Recovery Arrangements.

"I've also spoken to the Prime Minister about it."

Mr Morrison visited the Huon Valley on Monday, but neither he nor Mr Hodgman mentioned the special funding request.

A helicopter douses flames in Tasmania's south-west wilderness. ( ABC News )

Mr Hodgman is yet to receive a response from the Federal Government.

"Tasmania has quite extraordinary circumstances in terms of the world heritage property and its asset value to our state, but also the need for us to apply appropriate resources to protect it when it under threat as we've done," he said.

The request is not without precedent though, the Federal Government contributed additional funding for the 2016 fires.

Call for disaster unit

Greens Senator Nick McKim urged the State and Federal Government to act.

"These fires aren't done yet, they're still burning in our world heritage area," he said.

"These fires have devastated obviously a really beautiful and important part of Tasmania, and we need to make sure there's more resources available to help our fire fighters in the future.

"This is too important an issue, with climate change upon us, to be an argument about who pays."

Senator McKim also wants a better system of responding to national emergencies.

"We think the Federal Government should be forming a disaster emergency response unit that could be anywhere in Australia in four hours, to deal with everything from the floods in Townsville to the remote area wilderness fires in Tasmania," he said.

"That's something we're proposing for the future.

The Federal Government has been contacted for comment.