Don Greenlees, Jakarta – A human rights group claimed yesterday to have evidence that members of the Indonesian army's special forces, Kopassus, were implicated in the killing of two Americans and one Indonesian working for the Freeport copper and gold mine in Papua.

Citing testimony from an unnamed witness, Institute for Human Rights Study and Advocacy (ELS-HAM) official John Rumbiak said Kopassus soldiers had exchanged radio messages on the movements of vehicles carrying the three employees just prior to the August 31 ambush on a road leading to the mountaintop Freeport mine. He said the witness, a Papuan Kopassus informant, had on the day of the attack been close to the ambush site in the company of other members of Kopassus.

The witness alleged that, as the Freeport employees drove past, he overheard a member of the group send a radio message referring to the "target" vehicles. Based on this testimony and other factors, Mr Rumbiak said an investigation by ELS-HAM suggested "there is a strong indication" Indonesian soldiers were involved in the attack. The witness is now alleged to be in police protection in the provincial capital, Jayapura.

The attack has refocused domestic and international concern over conditions in Papua, where the local people have waged a long-running campaign for independence. The fact that two of the victims were American school teachers working for Freeport and that the identity of the attackers remains unknown, has raised the stakes for the Indonesian Government and the independence movement.

Inquiries by police and Freeport have yet to reach any conclusions over who was behind the attack. Investigators, the company and security analysts are divided on the issue of responsibility. Although most still suspect a hardline element of the rebel Free Papua Organisation (OPM) carried out the killings, they do not rule out the possibility that the perpetrators were soldiers or individuals in the pay of soldiers.

Mr Rumbiak said ELS-HAM had discounted the possibility of OPM involvement and he called on the US to co-operate with Jakarta in establishing a more thorough investigation. But a police spokesman in Jayapura, Daud Sihoimbing, denied any conclusions had been reached and said the OPM remained a suspect. The latest allegations of military involvement in the killings coincided with an Amnesty International report alleging a security operation in Papua between April and October last year resulted in widespread abuses, including the deaths of seven people.

Amnesty said the operation, led by the Indonesian paramilitary police unit, Brimob, highlighted the dangers of security forces being employed to protect commercial interests in Papua, such as the Freeport copper and gold mine.