An out-of-control bushfire that threatened homes in northern Tasmania was deliberately lit, authorities say.
The blaze at Ravenswood, a Launceston suburb, was reported around 3.20pm on Wednesday and sparked a watch and act alert.
Crews were working to contain the bushfire, which had burned 184 hectares at midday on Thursday.
"Crews are expected to remain on the ground for several days, with fire weather forecast to be moderate (on Thursday) and high across the weekend," Tasmania Fire Service operations officer Rick Mahnken said.
Investigators have determined the bushfire, which didn't cause any structural damage, was deliberately lit and has been passed to police for investigation.
A smoke alert was in place for Ravenswood.
Tasmania Police has encouraged anyone with information to come forward and have flagged an increased officer presence in the area.
