The fire, which has consumed about 100 hectares (250 acres) of forest, broke out in the late afternoon after high winds apparently fanned flames coming from a burning car body shop at Viege.

Police said a large part of the affected zone is inaccessible on foot and that the work of firemen and helicopters was complicated by strong winds, which has since weakened.

Late Tuesday night, parts of Viege are still engulfed by smoke.

No buildings were immediate threatened by the fire, but residents of the nearby village of Visperterminen, some three kilometres (two miles) to the south, were evacuated.

Several Swiss cantons have over the past week imposed bans on lighting fires in or near forested areas amid one of the worst droughts to hit the country in 150 years.