Tasmania Fire Service chief officer Chris Arnol on Friday said hot and windy conditions would contribute to high fire danger for the area on the weekend.

He said the uncontrolled fire at Fingal still posed a threat to the township though he was confident it would be controlled before it could spread that far.

"Fire activity as it has been tracking of an evening has become very erratic," he said.

MORE ON THE FINGAL FIRES:

"The winds are really complex. We've got seabreezes fighting the prevailing winds."

Mr Arnol said some Mangana residents had attempted to return to their homes which was discouraged at this stage.

"We must stress that we're not letting people back into that area because it is too dangerous," he said.

Mr Arnol said an uncontained fire front in Mount Malcolm area had placed the Douglas-Apsley National Park under threat.

He predicted the fire could spread at a pace of 550 metres an hour on Saturday with flame heights to 10 metres and spot fires 1.5 kilometres ahead of the fire body.

"We don't want people to be alarmed but we do need people to be aware," Mr Arnol said.

"It's not predicted to go into Bicheno but it could certainly frighten a few people who are nearby."

He said fire fighters had dealt with 196 fires over the week which had been reduced to 14, of which four were of a major concern.

This included the fire at Fingal, two controlled fires in the Derwent Valley and Strathgordon, and a fire west of Hobart.

A total fire ban has been declared for state's North and South on Satuday.

Mr Arnol said the ban would not apply to the North-West and West Coast although restricted fire permits would be in place.

Acting Police Commissioner Scott Tilyard said a team of detectives continued to investigate the circumstances around the deliberately lit fire at Fingal.

He said there were investigations into other smaller fires in the state which were believed to have been intentionally lit.

"The community are our eyes and ears," Mr Tilyard said.

He said people should call 000 if they saw anyone who was intentionally lighting a fire or call 131 444 to report any other suspicious activity.