Indonesia is investigating reports that 31 construction workers were shot dead by separatist rebels in restive Papua province, the public works minister said on Tuesday, as he halted construction in the area.
If the killings are confirmed, they would mark the deadliest bout of violence in years to hit the region, which has long been at the centre of a low-level independence insurgency.
"We're shocked and saddened to hear the media reports this morning," public works minister Budi Hadimuljono told reporters in Jakarta.
"All work is going to be suspended (in the area) given this incident," he added.
The employees of state-owned contractor Istaka Karya were building bridges and roads as part of efforts to boost infrastructure in the impoverished region, he said.
Citing a local police officer, Indonesian media reported late on Monday that the workers were shot dead on Sunday in Nduga, a district in the centre of the far-flung region on the western half of New Guinea island, just north of Australia.
The alleged killings were reportedly carried out by rebels who have led a decades-long insurgency against Jakarta's rule. Indonesia routinely blames separatists for violence in Papua.
Some workers reportedly managed to escape the shootings, which were allegedly sparked by separatists angry at some workers who were taking pictures of a pro-Papua Independence activities.
Foreign media need permission to report from Papua and obtaining reliable information is difficult.
The alleged killings come as more than 500 activists - including an Australian - were arrested in a nationwide police crackdown that coincided with rallies on December 1, a date many Papuans consider should be the anniversary of their independence from the Dutch.
Papua declared itself an independent nation on that date in 1961, but neighbouring Indonesia took control of the region by force in 1963. It officially annexed Papua in 1969 with a UN-backed vote, widely seen as a sham.
Jakarta keeps a tight grip on the resource-rich region, which has been the scene of a low-level independence insurgency since the late Sixties.
Papua experienced several outbreaks of violence this summer including the killing of three local people, allegedly by rebels.
The deaths followed a gunfight that saw a small plane carrying 15 police officers - sent to oversee the local elections - was shot at as it landed at Nduga.
Some of the violence has been centred on protests against a huge gold and copper mine operated by US-based firm Freeport McMoRan - a frequent flashpoint in the local struggle for independence and a bigger share of the region's rich resources.