The governor of Chiang Mai has announced a 10,000-baht reward to anyone who provides information that leads to the arrest of a person who sets fire to forest areas.

Governor Nirat Sitthithaworn said on Sunday the reward was a bid to control smog.

"The reward is for each person who provides information that leads to the arrest of a person who starts a fire in a forest. When a police interrogator agrees to take legal action, meaning that there is a culprit, the 10,000-baht reward will be paid that very same day," the governor said.

According to the governor, local officials focused on curbing burning in farmland during the first two months of this year and the measure prevented field burning in more than 200,000 rai of agricultural land in Chiang Mai.

Deliberately-set forest fires increase in March to help the collection of forest products and to clear land for corn.

On Sunday Chiang Mai had the highest level of PM2.5 in the country.

PM2.5 levels were at 64 microgrammes per cubic metre of air in Chiang Mai over the past 24 hours. The safe threshold is at 37.5µg/m³.