The Department of National Parks, Wildlife and Plant Conservation ordered the closure of the Chiang Dao Wildlife Sanctuary in Chiang Mai province after several man-made hotspots were found in sensitive ecological areas.
Attapol Charoenchansa, the department's chief, said the sanctuary is closed until forest officials resolve problems related to forest encroachment, forest burning and homestay ventures.
He said a huge number of forest areas with fertile ecological systems and biosphere reserves have been destroyed by man-made fires.
Chiwat Limlikit-aksorn, director of the National Park Office, and his team earlier visited the area to deal with forest encroachment and homestay activities. A report published shortly after said hotspots were found in the area.
"Urgent care must be provided in the area because it's where rarely-seen plants grow. It is now under heavy threat from man-made fires," Mr Attapol said, adding the country's biosphere reserve could disappear without strict prevention measures.
The department will set up a special unit consisting of law enforcement, land management and rehabilitation teams to tackle the issue, he said, adding it will also invite the army to help curb illegal drug trades and outlanders.
He also said the conflict between locals and forest authorities is the main cause of forest fires in the area, adding some locals encroach on the forest for agricultural and homestay activities, which are against the law.
"Some people don't follow the law," he said. "So, we needed to have a serious talk and closing the area was one of our initial measures. The park will be closed until all the issues are settled."
A total of 41,874 hotspots were found in the past three months in conservation areas around the country. Officials have taken legal action in 140 forest fire cases in which 13 firefighters were injured, the department said.
Meanwhile, a forest fire was reported on Friday in Khao Samo Pun in Muang Prachin Buri district, an area in Khao Yai National Park. Sixty firefighters managed to control the fire within a limited area on Saturday.