Survivors of the 1965 anti-communist massacres in Indonesia say it is time for their government to acknowledge the existence of the mass graves across the archipelago.

Key points: Locals outside Semarang cast off taboo about speaking of the 1965 killings

Locals outside Semarang cast off taboo about speaking of the 1965 killings One former 1965 prisoner says he was due to be killed in the Semarang forest

One former 1965 prisoner says he was due to be killed in the Semarang forest Youngest survivors and witnesses to killings are now in their 70s and 80s

President Joko Widodo wants an inquiry into the location of the mass graves, but the man he has put in charge of the investigation — cabinet minister Luhut Panjaitan — has expressed scepticism about the massacres and asked the media to show him where the nation's mass graves are.

No one has ever been charged over the massacre of more than half a million people in 1965 which was sparked by a failed coup attempt that led to the deaths of six senior army generals.

The ABC visited two sites in Central Java and spoke to those who remembered what happened there.

Outside the town of Semarang, locals have cast off the taboo about speaking of the killings. They have even erected a monument to the prisoners who were brought here from a local jail and then murdered.

"The communists came wearing blindfolds, and their hands tied to one another," local Sukar said.

"I heard the rifle shots between midnight and 1:00am."

The next morning, when the soldiers had left, the village head asked him and several others to help clean up the site.

"We found two holes filled with bodies covered by thin soil. Their body parts were uncovered. I collected them and buried them," he said.

'They are innocent people'

One of the victims was Sachroni, a member of the local farmers' group.

The path to the mass grave at Semarang. ( ABC News: Adam Harvey and Ari Wuryantama )

Five decades on, his now 80-year-old nephew, Muchran, goes to the mass grave to pray for those killed there.

"I pray, so the rest of us who are still alive, will have their blessings. We expect their spirit to wake up," he said.

"I want this grave to be taken care of. Don't abandon them — for humanity's sake. They are innocent people."

Mr Widodo has said he wants an inquiry into 1965, but the subject remains taboo in Indonesia.

Books and films on the subject are banned in Indonesia, and the Government does not accept that the killings were officially sanctioned — even though many prisoners were brought directly from jail to the killing grounds.

Eko Sutikno was due to be executed at this Semarang site in 1965 but his place was taken by another prisoner. ( ABC News: Adam Harvey and Ari Wuryantama )

One former 1965 prisoner, Eko Sutikno, said he was due to be killed in the Semarang forest.

"There were four people with a similar name to mine, 'Tikno', and that night, when they called out my name, someone stood up for me answering 'that's me sir'," Mr Sutikno said.

"He realised that once your name is called you will never return, but after the suffering and torture, he considered it better to die than continue to live."

Near the town of Pati, a villager called Radimin was imprisoned and then brought to a forest where holes had been dug. He thought he was about to be killed.

"I was to say goodbye to my wife, my mother and a relative of mine before I go. They were all crying — they thought it was my last goodbye."

'I am the only witness left now'

Villager Radimin stands in a grave that was dug for the 1965 massacre but was never used or filled in. ( ABC News: Adam Harvey and Ari Wuryantama )

The killers dug more holes than they needed and in the Pati forest, the excavations are clearly seen.

Radimin showed them to the ABC and recalled what he saw 50 years ago.

"Each person was held [with] two men holding their shirts by the shoulder, up to the edge of the hole," Radimin said.

"They threw the men into the hole, while another guard pushed the men's waist.

"Then once they were in the hole they shot them. One man stayed alive, even after they shot him in the head. They shot him more, then buried him with soil — that's how he died."

The murderers wore the yellow uniform of a local militia called Garuda Pancasila Youth.

Radimin said he was still not sure what his offence was — he suspects it was because he had disobeyed an order from the son of an important local figure to work in his rice paddy.

The youngest survivors and witnesses to the killings are now in their 70s and 80s.

Time is running out for the Government to collect their evidence.

"It was only me and Mr Sarimin who helped bury them," Sukar from Semarang said.

"But Sarimin died a long time ago, I am the only witness left now."