Oliver Milman – Helicopters supplied by Australia were used by Indonesia in a "genocidal" crackdown on civilians in West Papua in the 1970s, a new report has claimed.

The report, conducted by the Hong Kong-based Asian Human Rights Commission, says two Iroquois helicopters from Australia were among the aircraft deployed by the Indonesian military in the central highlands of Papua in 1977 and 1978.

The commission said the military operations resulted in the death of more than 4,000 indigenous Papuans, often from aerial assaults by helicopters and OV-10 Bronco planes, supplied by the US.

The report accuses Indonesian soldiers of "brutal and inhumane" treatment of civilians, with survivors telling the AHRC that officers forced elderly Papuans to eat their own excrement, while those arrested by the military were lined up and indiscriminately shot.

The report paints a disturbing picture of sexual violence against Papuan women, with accounts of rape and sexual abuse "common". Some women had their breasts cut, while others were buried, burnt and boiled alive.

In one incident, villagers were bombed with napalm as they awaited planes they were told would deliver aid from Australia.

The military campaign intended to quash support for the separatist Free Papua Movement, which was popular in the region.

The AHRC said accounts of the killings, which took three years of research, amounted to genocide under UN conventions, with high-ranking Indonesian military officials, including former president Suharto, implicated.

Basil Fernando, AHRC director for policy and programme development, said: "The long period of authoritarianism under Suharto has profoundly silenced the Indonesians from discussing its dark history related to Papua.

"Without any recognition from the government and the public at large in Indonesia on the state-sponsored wrongdoings in Papua, the ongoing conflicts in the area will only continue."

"There should be genuine efforts from the government to provide justice for the Papuans, one of which is by fulfilling their right to truth."

The report calls for a truth and reconciliation commission to be established, the lifting of "unreasonable and disproportionate" restrictions on freedom of expression on West Papua and the encouragement of an "open discourse" on the violence in the region.

Jennifer Robinson of International Lawyers for West Papua said: "AHRC's work in documenting the mounting evidence of the genocide committed by Indonesia in West Papua is invaluable.

"For too long the UN and the international community have neglected the suffering of West Papuans as a result of Indonesia's crimes. Without recognition and justice, there will be no peace in Papua."

The Australian government says it is studying the report.