SYDNEY (AFP) - Several people were missing feared dead on Sunday after wildfires swept through the Australian island of Tasmania, destroying more than 100 homes and forcing thousands to flee.

Acting Tasmania police commissioner Scott Tilyard said officers were investigating several missing persons reports after fires ravaged southern Tasmania state, razing scores of homes.

"I am fearful that someone may have died in this fire... it is a very distinct possibility still and I think people need to brace themselves that that may occur," Mr Tilyard told reporters, saying there were grave fears in a "handful" of cases.

"Whilst we have had no known deaths associated with these fires at this particular point in time, I want to make it quite clear that it is still far too early to confirm that that is not the case," he added.

Police were going door to door in the worst-hit towns of Dunalley and Boomer Bay to search for the missing and confirm no lives had been lost.

Almost 3,000 people were evacuated from their homes and many were stranded Sunday in emergency shelters as the fires raged to the east and west of the state capital Hobart, cutting off roads.

The Tasmania Fire Service (TFS) downgraded two major blazes from emergency to watch-and-act status, with calmer conditions bringing a much-needed reprieve for fire crews ahead of worsening fire weather later in the week.

"At the moment we are still working with a number of fires across the state," TFS chief officer Mike Brown told reporters.

"We are going to be in this situation for a number of days yet." Mr Brown estimated that there were "hundreds of kilometres of uncontrolled fire" still burning in heavily forested areas that are difficult to access.

"We have got a lot of work ahead," he said.

High winds which fanned the worst of the blazes had dropped off, giving crews a valuable opportunity to contain some 20 fires still active before conditions were expected to worsen again on Thursday, said TFS spokesman John Holloway.

"(Crews will be) doing some more active firefighting rather than just property protection," Mr Holloway told ABC Radio.

"We're looking at some warmer weather again through on Thursday, so if we've got this window to work on these fires and get some form of control around them, we're going to take that opportunity when we can."

Hot and dry summer conditions have seen fires start in a number of Australian states this month, with heatwaves in several major cities.

Wildfires are a fact of life in arid Australia, where 173 people perished in the 2009 Black Saturday firestorm, the nation's worst natural disaster of modern times.