The men were killed in the remote mountainous district of Nduga in an attack that was blamed on the Free Papua Movement.
The military arm of the movement said on Facebook that it viewed the workers as soldiers and casualties of a war against the colonialist oppressors in Jakarta.
Most of the workers were killed at their construction site, while seven apparently hid at a politician’s home before being found and murdered.
Military spokesman Colonel Muhammad Aidi said a construction worker who took a photograph of separatists celebrating what they consider their independence day on December 1 appeared to have caused the attack.
Defence minister Ryamizard Ryacudu said: “They were not just criminals, but separatists. They want to separate Papua from Indonesia, so they must deal with the military, not the police. There will be no negotiations. They surrender or we finish them off.”
Some of the attackers used spears and arrows, the military claimed.
The employer, Istaka Karya, a state-owned construction company, is building one of 14 bridges along the 280km highway. All bridge construction in the sprawling province has been suspended.
Papua on the western half of New Guinea was annexed by Indonesia after the Dutch colonialists left in 1963. It was then incorporated into the country after a 1969 “referendum” of tribal representatives.
Guardian journalist George Monbiot said 1,026 men were seized by the Indonesian authorities in 1969, some of their families were taken hostage and they were told to vote in favour of occupation or their tongues would be ripped out. One man who refused was apparently shot dead. The rest unanimously voted in favour of joining Indonesia.
“That is the sole basis on which Indonesia claims proprietary over West Papua,” Monbiot, the author of Poisoned Arrows about the province, told the BBC.
The Indonesian military has long been accused of rights abuses against Papua’s ethnic Melanesian communities, including extrajudicial killings of activists and peaceful protesters.
Papua, Indonesia’s largest province with just 5 per cent of its population, is rich with minerals, oil and timber and the world’s largest gold and second largest copper mine. Almost none of the profit from the giant Grasberg mine (pictured) goes to Papuans and it is also the country’s poorest region, with 28 per cent of residents living below the poverty line. It has some of the worst infant mortality and literacy rates in Asia.
The foreign-owned Grasberg mine. Picture credit: YouTube