There are concerns a bushfire burning in Tasmania's remote south-west wilderness area could threaten an "irreplaceable global treasure".

The fire, —at Olegas Bluff, inside the Franklin-Gordon Wild Rivers National Park — started on Tuesday and has burned more than 300 hectares of bushland.

That area is famous for its ancient Huon pine trees and rugged landscape, ranging from button grass moorlands to eucalypt and rain forests. 

In an effort to contain the blaze, Tasmania's Parks and Wildlife Service is using four light planes to water-bomb the western boundary and has sent in a remote area fire-fighting team. 

"The remote crews will be prioritising their fire-fighting attacks around some sensitive natural and cultural values on the fire ground," Parks and Wildlife incident controller Alex Bradley said.

"They will get a remote kit airlifted into them, which contains fire-fighting gear — from water bladders, pumps, hoses and a range of other gear — needed to set up mobile water supplies to pump out of existing rivers."

Journalist and environmentalist Andrew Darby said he was concerned about how close the fire was burning to the Truchanas Huon Pine Reserve, which includes a stand of ancient pines. 

Huon pine is found only in Tasmania and can grow for up to 3,000 years. 

"The Truchanas Huon Pine Reserve is an irreplaceable global treasure," Mr Darby said.

"You can just imagine that something as precious as this must be protected, it absolutely must be protected.

The Truchanas reserve is named after Olegas Truchanas, a pioneering photographer whose images of the Tasmanian wilderness became world famous. 

He was closely associated with the fight to save Lake Pedder from being flooded by the Hydro-Electric Commission and battled to save the Huon pine forest that now bears his name.

Mr Bradley said the fire was only a "couple of kilometres" from the reserve and the incident management team, set up at Strathgordon, was looking at the best way to protect it.

"We've got options, such as different types of aircraft. We've got ground crews that are hoping to suppress the fire long before it gets there," Mr Bradley said.

"If it burnt through [the Truchanas reserve] under the conditions that we're seeing today on the fire grounds, low to moderate conditions, it probably wouldn't do too much harm.

Bureau of Meteorology duty forecaster Anna Forest said winds in the area were blowing around 40 kilometres per hour and it was about 18 degrees Celsius.

"At the moment, it's dry and windy, which is not the best for a fire," she said. 

Winds are likely to ease on Friday and cooler conditions are on the way.

"It's going to depend a lot on the terrain, exactly which side of a hill you're on, as to exactly the temperature you're going to get," Ms Forest said.

"It could be just enough to dampen things down a bit, but not enough to dampen any flames that are around."

Several walking routes within the national park are closed because of the fire, including access to the Hamilton Range and Truchanas Pine Forest Reserve via the Gordon Dam, the Prince of Wales Range, and Pearce Basin to the Denison River.

Visitors to the area are advised there will be increased road traffic and the presence of aircraft around the village at Strathgordon.