Nearly 1,000 firefighters have been dispatched to put out a forest fire that started Tuesday in north China's Inner Mongolia Autonomous Region, local authorities said Wednesday.

The fire broke out in the Haosengou forest farm in the city of Arxan of Hinggan League. High mountains, steep slopes, dense vegetation and strong winds with changing directions have posed challenges to fighting the fire.

About 450 firefighters from the autonomous region's forest fire station and another 500 local firefighting forces have been sent to the frontline as of Wednesday afternoon.

According to an aerial survey, the fire perimeter is about 18 km. Two helicopters have also been dispatched to fight the fire.