Achmad Sukarsono and Jerry Norton, Jakarta – Indonesian troops fanned out through thick jungle in Papua province on Monday in search of an armed band that killed three people in the bloodiest clash involving foreigners since a long-simmering rebellion began.

The Saturday attack, near the world's biggest gold and copper mine in Indonesia's rugged easternmost province, was more bad news for a nation struggling to convince investors and aid donors it is moving toward stability and putting a lid on violence.

"We are going to hunt them although you know it's not easy here. It's jungles and ravines and mountains ... To find them is like to find a small needle in a soccer field," Papua regional military chief Major General Mahidin Simbolon said.

Speaking by telephone from the military operations area, he blamed the Saturday ambush on separatist rebels.

Papua province, formerly Irian Jaya, borders independent Papua New Guinea on an island off the north coast of Australia.

"They're indeed separatists. They're OPM. But we don't know which faction yet," he said, referring to the Free Papua Movement that has fought a low-level rebellion against Jakarta's rule for decades.

The rebellion is sparked by many causes. Indigenous Papuans differ ethnically from most other Indonesians and are generally Christian or animist while the country as a whole is Muslim. Many also object to the heavy proportion of revenue from the resource-rich province that flows to Jakarta.

Revenue source

One symbol of that economic complaint is the mine operated by a subsidiary of US-based Freeport-McMoRan Copper and Gold Inc.

On Saturday, a gang of what the military said was 15 armed gunmen ambushed a convoy of vehicles carrying mostly American teachers and their families from an international school that serves mining operation staff.

In a hunt for the attackers on Sunday troops exchanged shots with an armed band, killing one of its members – who appeared to be an indigenous Papuan – and suffering one wounded themselves. Simbolon said the group was the one responsible for the ambush. "We shot one and we are looking for the other 14," he said.

Asked whether the group was linked to the separatist Papua Praesidium Council, which seeks independence through peaceful means, Simbolon said: "They have the same idealism. Both of them want to separate this area from Indonesia. One is a military wing. The other is a political one. Whether they have some cooperation in this incident, I won't make any conclusion. You figure it out yourself."

Spent ammo

Simbolon said over the weekend that soldiers found spent cartridges at the ambush site from weapons including M-16 rifles and guns that were standard issue for Indonesian military in the 1970s. He strongly denied the military or police had had anything to do with the fatal attacks.

The gunmen in the Saturday ambush opened fire about two km from Tembagapura, a high-altitude town 3,300 km east of Jakarta which serves Freeport operations.

In addition to the three killed, Freeport said eight foreigners and two Indonesians were in the attack. The foreigners were school teachers at an international school in Tembagapura and their families. All were evacuated for medical treatment.

One wounded survivor, an Indonesian driver named Mastur, said the attack came fast. "I didn't see what happened. It occurred so quickly," he told Reuters in the Jakarta hospital to which he was evacuated on Sunday for treatment for a bullet wound. He said he heard firing but did not see who did the shooting.

The only other major incident involving foreigners in recent years in Papua occurred in 1996 when OPM guerrillas kidnapped 23 people including six Europeans in two separate incidents. A total of four Indonesian hostages were killed and the rest freed.

In a weekend statement, Freeport said it "deplored" the ambush of the convoy but its operations had not been affected.

Activists have criticised Freeport over its environmental record and impact on the local community in Papua. Freeport began operations in 1968 and defends its record, saying it makes an important contribution to the country and has spent millions of dollars in developing the local area.

Foreign Ministry spokesman Marty Natalegawa insisted on Sunday that the attack would not undermine the government's pledge to make the country safe for investment.

"It [the ambush] may have been deliberately committed to create a loss of confidence in Indonesia's security environment. The message is that we will not allow these rogue elements to disrupt the investment climate in Indonesia," he said.

Papua was incorporated into Indonesia in 1963. In 1969, a UN-run plebiscite held among local leaders resulted in a vote to join Indonesia. The vote has been widely criticised as unfair.