Heavy smoke from illegal fires set to clear land for plantations has blanketed parts of Indonesia’s Sumatra island, disrupting flights and hampering search efforts for the missing Malaysia Airlines jetliner, officials and a pilot said Thursday.

Forest and brush fires have raged for the past week, mostly in peat-rich Riau province, forcing schools to close. Children and the elderly have filled local clinics and hospitals, complaining of respiratory problems.

Forty-six hotspots were detected by satellite Thursday across Riau province, down sharply from 168 on Wednesday, said Raffles Brotestes Panjaitan, the Forestry Ministry’s director of Forest Fire Control. As much as 13,000 hectares (32,123 acres) of land in Riau has burned since early last month, according to government estimates.

Panjaitan said a thick haze was covering Pekanbaru, the provincial capital of Riau and the nearest city to the fires, sending a cloud of smoke to the neighbouring provinces of Jambi and West Sumatra. Visibility was reduced to less than 50 meters (yards) in some districts.

“The government has tried to halt the burning, but it has gotten out of control,” Panjaitan said.

The smoke has left more than 45,000 people with respiratory problems and eye irritation, said Zainal Arifin, who heads Riau province’s health office.

Provincial authorities urged people to stay indoors due to “hazardous” levels of pollution.

More In: World | International | News