Education department deputy secretary Andrew Finch said the department had made alternate school arrangements for parents unable to organise supervised care.

``Children attending Collinsvale Primary can be dropped off at Glenorchy Primary and Molesworth students will be accommodated at New Norfolk Primary,'' Mr Finch said.

``It is important that parents not leave their children at home unsupervised.''

More than 20 units from the Tasmanian Fire Service are battling the 300ha fire.

There are reports of embers, smoke and ash falling on Molesworth, Glenlusk, Collinsvale and the greater Hobart area.

The TFS said that the fire may affect the communities of Collinsvale, Glenlusk, Berriedale, Iron Stone Gully, Malbina and residents of Valley Road, Fehlbergs Road, Nelsons Road, Glen Lusk Road, Stock within the next six to 24 hours _ although there is no immediate threat to these communities.

There may be an increase in smoke at Mount Nelson, Lenah Valley and Hobart CBD as a result of strengthening winds and increased fire activity, the TFS said.

Collins Cap Road, Glen Dhu Road and Molesworth Road are currently closed to general public, with access only for residents.

More information will be provided today on whether the schools will open tomorrow.