Jakarta: Indonesia must do more to provide justice for victims of a 1960s anti-communist purge and their families, Amnesty International urged Wednesday, 50 years on from events that triggered one of the worst mass killings of the 20th century.

At least 500,000 people died in the killings across the archipelago that started after General Suharto put down a coup on 1 October, 1965, that the authorities blamed on communists.

Security forces supported local groups in conducting the massacre over several months, with many suspected of even weak links to Indonesia’s communist party killed, and hundreds of thousands of others imprisoned, some for years.

Suharto took power after the failed coup and ruled Indonesia with an iron fist for 32 years, with the necessity of the killings to rid the country of the communist threat becoming part of the official narrative and the perpetrators left unpunished.

Calls grew for action to come to terms with the dark episode after the dictator was toppled in 1998, but rights groups have criticised authorities for making little progress.

President Joko Widodo — who came to power last year and is viewed as a break from a string of rulers with links to the Suharto era — vowed to solve past rights abuse cases, but Amnesty said Wednesday not enough was being done.

‘Five decades is far too long to wait for justice for one of the worst mass killings of our era,’ said Papang Hidayat, Amnesty International’s Indonesia researcher, in a statement to mark half a century since the killings.

‘Across Indonesia, victims of the 1965 and 1966 events and their family members have been left to fend for themselves, while those suspected of criminal responsibility walk free.’

Widodo’s government announced in May that it would establish a committee to try to resolve past human rights abuses, but Amnesty noted that it did not have power to prosecute, meaning surviving perpetrators would still not face justice.

There has been speculation that Widodo’s government might issue an official apology for the killings but presidential spokesman Ari Dwipayana told AFP the president had not yet considered the matter.

However he added: ‘It is definitely an issue we are concerned about.’