Tas fire expands, close to heritage forest

A planned burn in Tasmania's Styx Valley has expanded in size and is just four kilometres away from world heritage-listed forest.

The fire began burning out of control on Wednesday near the Styx River, southwest of Bushy Park. It was lit by forestry authorities on Saturday following logging operations.

Late on Thursday night Sustainable Timber Tasmania crews conducted backburning to contain the bushfire.

On Thursday, STT said the fire spanned 130 hectares, but by Friday it reported the fire had spread across 175 hectares.

Despite the spread, the fire remains confined to land permanently zoned for timber production, STT said on Friday.

Nearby communities in New Norfolk, Bushy Park, Westerway and Gretna have been warned about smoke and ash in the area, but there is no immediate threat to lives or property.

"The current residual smoke was not planned and unintended," STT chief executive Steve Whiteley said.

"Sustainable Timber Tasmania is disappointed of the outcome of this regeneration burn and will undertake a post burn operational review to learn from this event."

He said the organisation would work with surrounding businesses such as wine growers and the tourism operators to "co-operatively adapt future management for mutual benefit".

Kayak tour operator Fiona Weaver has been trying to run tours on the stretch of the Derwent most affected by the smoke and told AAP on Thursday her clients have been distraught at the reason for the smoke.

Ms Weaver is deeply frustrated by Tasmania's recent tourism marketing campaign, "Come Down for Air".

"It's quite embarrassing for us when they turn up and there's a smoke-filled valley," she said.

The Bob Brown Foundation is calling for an end to post-logging incineration, saying it impacts native wildlife and local people.

"It is time these logging burns were consigned to the history books of shame," a statement on Friday said.

"It is scandalous that Sustainable Timber Tasmania is still trying to appeal to work co-operatively with the public."

Waterbombing aircraft are supporting the firefighting effort and locals have been warned to keep clear of falling water.

There are 14 STT firefighting crews on site, two Parks and Wildlife crews and five crews from a forest management company.

The Tasmania Fire Services on Friday said there was no immediate threat and that the blaze was "not out of control".