GORONTALO, Indonesia: Protesters have set fire to a mayor’s office on an Indonesian island to demand compensation over a mining company’s activity in their area, police said, adding that several arrests had been made.

The growing presence of mining companies on Indonesia’s main islands has caused riots and clashes in recent years over poor working conditions and land encroachment.

The unrest began Thursday in Pohuwato regency in Gorontalo province on mineral-rich Sulawesi island when a march involving some 2,500 protesters approached the local mayor’s office but no official was willing to meet with them, according to local media reports.

Community activists had organised a march to demand compensation over gold mining activity in their area by PT Puncak Emas Tani Sejahtera, a subsidiary of PT Merdeka Copper Gold which oversees the Pani Gold Project mine.

“Regarding the demo, the police are still working hard to investigate the riot that happened during the demonstration in Pohuwato,” Gorantalo police said on its website late Thursday, quoting spokesman Desmont Harjendro.

After the mayor’s office was set on fire, protesters headed to the local parliament to stage another demonstration, where the building was also damaged, according to reports.

Harjendro said “several protesters” were detained and that police were guarding the sites.

“They will be questioned regarding the violent demonstration that ended in the destruction of several facilities including the burning of Pohuwato mayor’s office,” he said.

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

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,” he said in a statement Thursday.

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