Police in Indonesia’s Riau province have arrested 26 people for allegedly starting forest fires as choking haze prompted authorities on Sumatra island to declare a state of emergency, an official said today.

Riau on Tuesday declared that forest fires have reached emergency levels in seven of the province’s 12 districts and asked the central government to intervene.

“A helicopter surveillance of industrial forest plantations shows that fires are so bad that large water-dropping aircraft are needed to extinguish them,” said Sutopo Nugroho, spokesperson for the National Disaster Management Agency.

Nugroho said police in Riau had arrested 26 people on suspicion they had started some of the fires.

Past fires have been blamed on plantation owners who illegally use the slash-and-burn method to clear land.

Smoke from forest fires on Sumatra is an annual dry season hazard that often affects neighbouring Malaysia, Singapore and Thailand.

- dpa