Anti-mining protesters have set fire to a mayor's office on an Indonesian island and damaged the local parliament building, according to police.

Some 2,500 protesters demanding compensation from a gold mining company marched Thursday to the local mayor's office in Pohuwato regency in Gorontalo province, Sulawesi Island. When no official met them, they set it on fire, local media reported.

The protesters then headed to the local parliament to stage another demonstration, and damaged it, according to reports.

The demonstrations are now under investigation, Gorantalo police spokesperson Desmont Harjendro said.

"Several protesters" were detained and that police were guarding the sites, he added.

Harjendro warned other protesters they would be arrested if they engaged in violent attacks or damaged public property.

Activists are demanding compensation from PT Puncak Emas Tani Sejahtera, a subsidiary of PT Merdeka Copper Gold which oversees the Pani Gold Project mine in the area.

Boyke Poerbaya Abidin, president director of Merdeka Copper Gold and PT Puncak Emas Tani Sejahtera, criticized the demonstrators.

"We deeply regret the incident and we condemn the violent acts by the irresponsible protesters that has caused damages," Abidin said in a statement Thursday.

He said the mining project was operating on a government-approved license.

WITH AFP