An image of a controlled burn of Namadgi National Park in March 2013.

An image of a controlled burn of Namadgi National Park in March 2013. Photo: Katherine Griffiths

A large amount of smoke over Namadgi Park will be visible from Canberra on Wednesday as firefighters begin the biggest controlled burn in the territory in three decades.

Fires will be started in remote trails and from a helicopter over five days.

Fire manager Neil Cooper said the burn followed three weeks of extensive burns in Namadgi.

Covering 6000 hectares, the Smokers Trail burn will be bounded by Corin Dam in the west, Corin Dam Road in the north, Smokers Trail in the east and Cotter Hut Road in the south.

"From start to finish the burn could take more than 10 days to complete," Mr Cooper said

The control burn will be 20 kilometres from Canberra and at high altitude which is expected to make smoke more visible.

"Every effort is made to conduct burns in weather conditions that will minimise the impact of smoke in the area," Mr Cooper said.

The national park has been too wet for controlled burning for the past three years. Conditions have been more suitable this autumn.

In a water catchment area, the Smokers Trail burn will cover rugged, inaccessible bushland sheltering rare and threatened animnals and plants.

Mr Cooper said ecologists had assessed the bushland to help plan areas to be burnt.

"Several sphagnum bog areas have been excluded from the burn area.

“In addition, all work vehicles will undergo a weed wash before entering onto the fire ground to minimise the introduction of weeds."

Experienced and trained firefighters and volunteers would burn the areas, which would be closed to walkers.

Signs would be erected and information made available at the Tidbinbilla and Namadgi visitor centres, including alternative walking areas in Namadgi National Park.