Rokan Hilir, Riau province (ANTARA News) - Tens of hectares of peatland in Rokan Hilir district were on fire again on Friday after they were ablaze last week, a source said.

"The cause of the fire is still unknown," Surya Arfan, head of Rokan Hilir district`s Environmental Impact Supervision Agency (Bapedalda), said here Saturday.

He said a forest fire prevention team was still at the location to extinguish the fire and observe the situation there.

Personnel from the environmental supervision agency, the provincial forestry office and PT Chevron Pacific Indonesia (owner of half of the burning land) were trying to extinguish the fire on an area covered by a three-meter-deep peat layer.

"The team will also look out for the possible formation of new hot spots there," he added. Meanwhile, Rokan Hilir District Chief Annas Ma'mun expressed concern over the incident.

He asked all parties to stay alert to prevent more fires.

Earlier, Marzuki, chief analyst at Pekanbaru's Meteorology and Geophysics Agency (BMKG), had said the NOAA satellite had detected 58 fire hot spots in Sumatra forests.

"There are at least 58 fire hot spots in Sumatra now. Most of them are located in South Sumatra and Jambi provinces, namely 20 in each of them, and eight in Jambi province," Marzuki said.

Five of the fire hotspots appeared in Rokan Hilir, one in Bengkalis and two in Pelalawan, he said.

"The fire hot spots have formed due to the hot weather, with the temperature reaching 34.3 degrees Celsius in Riau," he added.

Marzuki predicted more fire hot spots would form in the days ahead due to the low precipitation. In Riau there was still some rainfall but when and where it would happen was hard to predict.(*)