Jakarta – The discovery of a headless corpse and the torching of houses have heightened tension in a district of Indonesia's Borneo island where at least 500 people were killed in over six weeks of ethnic violence, police said Monday.

"The corpse was found some 10 kilometres out of town yesterday [Sunday]," district police chief Petrus Hardono told AFP from the district town of Sampit in Kalimantan. He said that the victim was believed to be a Madurese migrant who had come out of his jungle hiding.

"I think he was like the others on Saturday, he must have been caught while sneaking out of the jungle in search for food," Hardono said refering to five other Madurese migrants who were killed in Sampit on Saturday.

But a local district official said that people did not venture outside their home once darkness had set in. "We are begining to get worried as rumours speak of armed Madurese planning to attack our town and exact revenge," said the official who declined to be named.

In Pangkalan Bun, the main town in the neighbouring district of Kotawaringin Timur, two houses left vacant by their owners were set on fire in the night of Saturday to Sunday, the district police chief Jusman Aer told AFP.

"Only two empty houses were burned," Aer said, adding that the local police and military forces have been reinforced by 100 policemen and 1,140 soldiers from outside the province.

"We now have 380 policemen and 1,289 soldiers," he said. "We have deployed them across the districts, including in the strategic areas in Pangkalan Bun. We hope that with their presence, people will feel secure," Aer said.

In the Central Kalimantan district of Kapuas, 44 empty houses were torched on Sunday near the town of Anjir Serapat, police said.