Indonesian police have arrested 72 people accused of setting fires in forests and peatlands, as severe blazes across central and western parts of the country produced widespread haze that crossed into neighbouring Malaysia. The fires are affecting areas on the islands of Borneo and Sumatra, where authorities are investigating 89 suspected forest and land-fire cases across nine provinces.

Mohammad Irhamni of Indonesia’s police special crime investigation division said most suspects are accused of deliberately burning land to clear it cheaply for farming or plantations. Police are also examining whether companies financed the fires. Irhamni said authorities would not only act against people on the ground, but would seek to identify those who benefited and those behind the burning. The accused could face up to 15 years in prison.

Indonesia’s environment ministry identified more than 3,700 fire hotspots in Borneo and over 1,700 in South Sumatra on Sunday. Visibility in some areas fell to 10 metres. Drought and El Niño have worsened conditions, while underground peatland embers risk reigniting fires. Indonesia has begun artificial-rain operations in Kalimantan and deployed 30 helicopters there and 22 in Sumatra. In Malaysia’s Sarawak, haze shut nearly 600 schools, affecting about 200,000 students.