Fire causes highway hazard in Tas

A total fire ban has been declared for northern parts of Tasmania.

Smoke from a bushfire in central Tasmania is causing a traffic hazard on one of the state's major highways.

Authorities issued a warning for motorists using the Midlands Highway on Saturday, after a blaze broke out in scrub on both sides of the road, just south of Oatlands.

"The Midland Highway is being affected by thick smoke blowing across the highway, reducing visibility in both directions," police said in a statement.

Fire crews are fighting the 100-hectare blaze using ground tankers and have also called in water bombing aircraft.

There is no immediate threat to property.

Amid dry conditions and high temperatures, parts of central and northern Tasmania are subject to a total fire ban on Saturday.