At least four teenagers were shot dead in eastern Indonesia's restive Papua province in clashes with security forces, authorities said Tuesday, although rights campaigners accused police of opening fire on protesters.

Monday's incident was the latest flare-up in violence in the eastern region, where poorly armed fighters have been waging a low-level insurgency against Jakarta for decades on behalf the mostly ethnic Melanesian population.

There were conflicting reports about what happened. Police said that four people died when several hundred protesters attacked military and police posts in the remote Madi area, in mountainous Paniai district, and it was not clear who fired the shots.

But Andreas Harsono, a Human Rights Watch campaigner in Indonesia, said five high-school students aged 17 and 18 were shot dead by security forces who fired live rounds into a crowd of protesters.

It is difficult to independently verify information from Papua, as Jakarta keeps a tight grip on the resource-rich region with a heavy police and military presence and there are restrictions on foreigners reporting from the area.

Police and rights activists both said tensions rose when local teenagers confronted the driver of a vehicle late Sunday. The driver was from a local military unit, according to Harsono, and returned later with a group of people who beat up the teens.

Overnight Sunday to Monday, a local election office was set on fire and then police and military posts were attacked, Papua police spokesman Sulistyo Pudjo told AFP.

"Suddenly there were victims, and we did not know who shot them," he said. "Four died, and 10 others were injured."

Harsono said that as well as those killed, 21 people were injured, and they included women and children. He said that he interviewed six people in Papua.

The police said two senior police officials as well as a forensic team were on the way to Paniai district to conduct an investigation.