A satellite observation on Sunday detected more hotspots on Sumatra Island and Borneo Island, the centers of Indonesia's palm oil plantation and habitats for endangered animals, a disaster agency official said.

On Sunday morning, the satellite detected 151 hot spots across the nation, most of which in the islands, significantly rising from 59 hotspots found nine days ago, said Sutopo Purwo Nugroho, spokesman of the national disaster management agency.

Of the total hotspots on Sunday, 57 of them were discovered on the Sumatra Island, mostly in Riau province, and 83 others in Borneo Island, Sutopo told Xinhua via phone.

He said agriculture and forest fires have occurred in both islands since 4 weeks ago as lacking of water supply amid dry weather has hampered firefighters to douse the blaze.

"The cause is similar, Indecency and burning, which means that the bush was intentionally burned," he said.

Riau province, home to the world's largest palm oil industry, has frequently endured forest fires as people burned land clearing for new plantation.

"In East Kalimantan of Borneo Island, it is not only plantation burned but also endangered species," said Sutopo.

Last year, the Indonesian government launched the biggest ever battle against massive forest fires occurring across the country, involving thousands of soldiers and scores of aircraft with assistance from foreign countries.

The fires have sent thick haze to neighboring Southeast Asian countries, causing health problems and a huge financial loss.