The fires include the fire at Mangana Road on Monday, which is still out of control. Residents were evacuated and still have not been allowed to return to their properties.

Tasmania Police Northern Commander Brett Smith said the behaviour was irresponsible.

He said investigations were occurring in regards to a number of fires over the past month.

"Police have reason to believe the main fire, as well as other fires in the area, have been deliberately lit," Commander Smith said.

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"Bushfires are devastating, destructive, and in this case has displaced people from their homes. Someone must know something about who is responsible for this fire."

Investigators are urging anyone in the community with information about who is responsible for these fires, or who saw anyone acting suspiciously around the time the fires started, to come forward.

Commander Smith said police had been investigating the possibility of fires being deliberately lit "for some time".

On Tuesday, Tasmania Police and the Tasmania Fire Service held a community forum to inform residents about the situation.

Police will have a "significant" presence in the area during the following weeks and say they are taking this matter "particularly seriously".

Six detectives are in the area on Tuesday and they are hoping residents will come forward with evidence, such as CCTV footage, that will lead to charges being laid.

Commander Smith said there were a lot of upset people within the community as a result of the announcement.

"It has a massive impact on the community itself and the residents at that community meeting yesterday were quite understandably concerned," he said.

"We are really hoping the people who have information will have the courage to come forward.

"We're pretty confident people not only know who the offenders are, but have seen things that will connect people to the fire."