A "people's tribunal" opened hearings in the Netherlands Tuesday intended to publicize allegations that Indonesian authorities were responsible for killing hundreds of thousands of suspected Communists 50 years ago.

Human rights lawyers acting as prosecutors charge the state of Indonesia in a nine-count indictment with crimes including murder, torture and sexual violence in the notorious killing spree from 1965-66 that left an estimated 500,000 people dead.

The bloodbath swept into power the dictator Suharto, whose authoritarian rule lasted for three decades.

The tribunal has no formal legal powers, but aims to shed light on what organizers call the darkest days in Indonesia's post-colonial history, and promote reconciliation by exposing the truth about the killings.

Prosecutor Sri Suparyati (center left) and prosecutor Uli Parulian Sihombing (center right). (AP/Peter Dejong)

One of the first witnesses to testify, academic Leslie Dwyer who has conducted research on the Indonesian island of Bali, said that 80,000-120,000 people were killed there between late 1965 and March 1966 and that the killings only started when government special forces arrived and began organizing local police and militias.

Dwyer said that in some cases only the most tenuous links to the Communists was enough to cost a person his or her life, including having sung or danced at an Indonesian Communist Party event.

Rights activist and former lawmaker Nursyahbani Katjasungkana, who helped establish the tribunal, said the government in Jakarta needs to be held to account for crimes committed in the past.

"The Indonesian government is responsible to fulfill and respect victims' rights," she said. "They have the right to justice, the right to truth and reparations."

Willy Wirantaprawira wears a badge of Indonesia's Democratic Party of Struggle (PDI-P) as he attends the “people’s tribunal”. (AP/Peter Dejong)

In 2012, Indonesia's National Human Rights Commission released a report concluding that the mass killings constituted gross human rights violations. However, the government dismissed it and refused to examine it further.

Indonesian senior officials this week dismissed the tribunal, and blamed the Netherlands for human rights violation during its colonization of Indonesia.

Activists also blame foreign powers, particularly the United States, Britain and Australia, for complicity in the killings, saying in the indictment that they provided small arms, communications equipment and even lists of potential victims to Suharto's forces.

The tribunal is expected to issue verdicts, which are not legally binding, next year.

A "people's tribunal" opened hearings in the Netherlands Tuesday intended to publicize allegations that Indonesian authorities were responsible for killing hundreds of thousands of suspected Communists 50 years ago.

Human rights lawyers acting as prosecutors charge the state of Indonesia in a nine-count indictment with crimes including murder, torture and sexual violence in the notorious killing spree from 1965-66 that left an estimated 500,000 people dead.

The bloodbath swept into power the dictator Suharto, whose authoritarian rule lasted for three decades.

The tribunal has no formal legal powers, but aims to shed light on what organizers call the darkest days in Indonesia's post-colonial history, and promote reconciliation by exposing the truth about the killings.