Tasmania fire
© ABC News / Damian McIver
A police road block at Forcett cuts access to the Tasman Peninsula this morning
Thousands of people are stranded and about 100 are still unaccounted for as out of control bushfires continue to burn in Tasmania.

The threat for the state's most destructive fires has been downgraded, but residents are being warned to remain vigilant.

More than 100 properties have been destroyed since the bushfires broke out in extreme heat on Friday, and police have warned that bodies may be found as teams go door-to-door in the devastated communities.

Thousands of people have been stranded on the Tasman Peninsula since the huge Forcett bushfire cut it off from the rest of the state, and this morning residents said food was beginning to run out.

It is understood the peninsula's main access road will open partially this morning, to allow a convoy of stranded people and supplies to get through.

Prime Minister Julia Gillard will tour the worst-hit town of Dunalley, south-east of Hobart, where more than 85 properties were destroyed, later today.

The Tasmanian Fire Service has downgraded the threat for the Forcett fire and another at Lake Repulse to 'watch and act'.

But fire crews say the drop in temperature and dew on the ground made it difficult to create containment lines around the Forcett fire overnight.

The Forcett fire has been the most destructive of more than 40 bushfires that are burning across the state.

Tasmania's chief fire officer Mike Brown says residents in Taranna and other Tasman Peninsula communities are being affected.

"There's a huge line of fire that's moving through the mountain regions on the Tasman Peninsula at the moment," he said.

"It's moving very slowly, but as the wind speed and wind direction moves around we may get the spotting activity that may impact on communities."

Tasmania's Emergency Services Minister David O'Byrne says a lack of rain in the coming week will worsen conditions.

"[That] will mean that not only the existing fires but other bushfire prone areas of Tasmania will be under threat," he said.

The Tasman peninsula is without power, with about 300 power poles destroyed by bushfires, and it will be at least a week before it is restored.

Stranded residents like John Hamilton say they are in urgent need of food and supplies.

"It'd just be good if we could get food through to the general populace. I understand a convoy has come through to the emergency centre at Nubeena, but a lot of families are just about run out of food now," he said.

"We need to feed the shops, we need to feed thousands of local people."

Mr Hamilton says there is also growing anger about emergency services maintaining road closures that have isolated the peninsula.

"We've just had people here in our car park and that's where the police sent them and they've just all gone back to their houses. The road needs to be open urgently. We're pretty frustrated, I assure you," he said.

Police say the roads will remain closed until they are safe and clear of debris.

Boats have been ferrying stranded residents and tourists from the peninsula to Hobart over the weekend, where an emergency centre had been set up at the City Hall.

Accommodation has now been found for everyone at the centre and it has been closed.

The Federal Government has activated emergency relief payments for affected residents and the Red Cross has set up a bushfire appeal.

Acting Police Commissioner Scott Tilyard told reporters on Sunday there are about 100 people with whom authorities have not had confirmed contact.

"That's not to say that those people necessarily have come to any harm, but obviously we can't totally eliminate that until we've had confirmed contact with those individuals," he said.

"We are still concerned about people. The premises that we've been through and checked so far, we haven't found any deceased people. We hope certainly that that continues.

"We also have to brace ourselves for the fact that we may locate one or more deceased people before we end the process."

Commissioner Tilyard says police are continuing to search buildings in the devastated communities of Dunalley, Boomer Bay and Marion Bay.

"We have teams on the ground now ... going through the process of having to go door-to-door on every fire-damaged property," he said.

"Some are shacks, some are houses, some are outbuildings. [We need to confirm] there are no people who have lost their lives at that particular location.

"That does take time and needs to be done properly."