A force of 50-70 rebels armed with military-grade weapons as well as spears and arrows attacked a group of 25 soldiers in Nduga district in a battle lasting several hours Thursday, said Muhammad Aidi, the military spokesman for Indonesia's easternmost Papua region.

The jungled highlands district was the location of a December attack by Papuan fighters on workers at a construction site for the trans Papua highway that killed 19. Large numbers of people have been displaced by military and police security operations since the Dec. 2 attack.

At least 31 people have died since early November in an apparent escalation of attacks by the West Papua National Liberation Army. The figure doesn't include unconfirmed civilian deaths that Papuan activists say resulted from security operations following the Dec. 2 attack.

Aidi said the military killed seven to 10 of the Papuan fighters but only found one body, saying the rest were carried away by other fighters. Sebby Sambom, a spokesman for the liberation army, said five soldiers were killed and admitted no deaths for the Papuan fighters. Both sides claimed to have captured weapons.

An insurgency has simmered in Papua, which makes up the western half of the island of New Guinea, since the early 1960s when Indonesia annexed the Dutch-controlled territory.

Discrimination against indigenous Papuans and abuses by Indonesian police and military have drawn renewed attention globally as Indonesia campaigns for membership in the U.N.'s human rights watchdog.

The exiled leader of the Papuan independence movement, Benny Wenda, in January presented a 1.8 million-signature petition calling for self-determination to the U.N. human rights chief in Geneva.

Aidi said the soldiers had arrived in the area to guard work on the trans Papua highway and the attack was unprovoked. According to Sambom, the soldiers had burned traditional dwellings and interrogated villagers, hoping to get information about liberation army positions.

Two helicopters sent to take the bodies of the three killed soldiers to the mining town of Timika were shot at but eventually landed after Indonesian forces returned fire, Aidi said.