TIMIKA, Indonesia - Separatists in Indonesia's restive eastern province of West Papua have shot dead at least four people, police said on Friday, identifying the victims as construction workers on a controversial and long-delayed road project.

Officials said the victims were working on the Trans Papua highway, a 4,300km-long project criticised by rights groups as harming the environment and threatening the indigenous rights of Papuans who depend on the land.

The West Papua National Liberation Army (TPNPB), the military wing of the main Papuan separatist movement, claimed responsibility for Thursday's attack.

It said its members shot dead four construction workers because they believed they were spies for the government in Jakarta.

The rebels "succeeded in shooting dead four Indonesian intelligence officers disguised as implementers of the Trans Papua Road Project", the group said in a statement.

Separatists in West Papua and neighbouring Papua province have waged a fierce insurgency against Indonesian security forces for decades.

They have stepped up attacks recently, targeting civilians they accuse of links to the state.

West Papua police spokesman Adam Erwindi said 12 workers were targeted in the attack and said a team of officers had been dispatched to the area.

"It is still being investigated. We will evacuate victims and visit the scene," he said during a press conference.

Indonesia says building the highway will facilitate goods and services to the local population.

The project in the under-developed, mineral-rich province has faced years of delays because of the rebel attacks.

Papua's Melanesian population shares few cultural connections with the rest of Indonesia - the world's largest Muslim-majority country.

The Indonesian military has long been accused of gross human rights abuses in the far-eastern region.

In July, rebels killed 10 people in an ambush as they transported goods, accusing them of working for the government. In March, separatists also shot eight telecommunications workers dead.

A former Dutch colony, Papua declared itself independent in 1961, but neighbouring Indonesia took control two years later, promising an independence referendum.

The subsequent vote in favour of staying part of Indonesia was considered a sham. AFP