Indonesian soldiers on Wednesday hunted for rebels suspected of killing as many as 24 construction workers in restive Papua province, as an eyewitness account supplied by the military described a grisly mass execution.

The survivor’s account detailed the killing of at least 19 people, which if confirmed would mark the deadliest bout of violence in years to hit a region wracked by a low-level independence insurgency.

A Facebook account purportedly run by the National Liberation Army of West Papua (TPNPB) said the armed group had killed 24 workers on the orders of regional commander Ekianus Kogoya.

Authorities have yet to confirm how many were killed in the weekend attack.

On Wednesday, some 150 military personnel were focusing their operation at Nduga, a remote mountainous region where a state-owned contractor has been building bridges and roads as part of efforts to boost infrastructure.

‘Inhumane acts’

Many Papuans view Indonesia as a colonial occupier and its building work as a way to exert more control over an impoverished region that shares a border with Papua New Guinea, an independent nation.

Indonesian president Joko Widodo said on Wednesday he backed the hunt for those behind what he described as the “alleged assault”.

“I have ordered the chiefs of the military and national police to chase and arrest all the perpetrators of these barbaric and inhumane acts,” he told reporters in Jakarta.

Police and military teams sent to the area on Monday came under rebel gunfire with one soldier killed and another wounded in the firefight, authorities have said.

Four workers – including three suffering gunshot wounds – were among a dozen civilians who have been evacuated from the area so far.

On Wednesday the military supplied an account from one survivor identified by his initials “JA” who claimed about 50 rebels entered the workers’ camp on Saturday and led them away with their hands tied behind their backs.

The following day the rebels shot dead a group of workers, while some tried to escape, the account said.

The attackers allegedly recaptured six workers and slit their throats, according to the uninjured witness, who said at least 19 employees had been killed in all.

Previous local media reports pegged the number of dead between 24 and 31.

AFP has confirmed with relatives that the eyewitness worked for the contractor in the area where the killings allegedly took place, but his account of a massacre could not be independently verified.