JAKARTA (AFP) - Indonesian rights groups on Saturday slammed the government's decision to grant parole to the convicted murderer of a prominent human rights activist poisoned during a flight ten years ago.

Pollycarpus Priyanto was serving a 14-year jail term for killing Mr Munir Said Thalib via arsenic poisoning on a national carrier Garuda flight from Jakarta to Amsterdam via Singapore in 2004.

Priyanto was granted parole on Nov 13 after eight years, said Mr Marselina Budiningsih, the warden of Sukamiskin prison in Bandung, 15km south-east of Jakarta. The prison refused to disclose when he will be released.

Several rights groups "regretted" the decision to grant the parole in the high-profile murder case, because even though involvement of the State Intelligence Agency in the operation to kill Mr Munir has been proven in court, the mastermind has not been punished. In 2008, a court cleared a former deputy head of the country's spy agency of masterminding the murder.

"The parole destroyed the sense of justice and democratisation in Indonesia," said Choirul Anam, the lawyer of Munir's wife.

An activist from the Human Rights Working Group Rafendi Djamin said parole should not have been granted due to the seriousness of the crime.

Mr Munir, who was 38 when he was killed, was a prominent critic of military human rights abuses and provided legal counsel to victims of state violence during former dictator Suharto's 32-year rule.

A former Garuda pilot, Priyanto's sentence went back and forth before court.

An original 14-year jail term was reduced to two years, for falsifying a document related to the death, and he walked free in 2006.

Two years later, his sentence was extended to 20 years and then reduced again last year to 14 years.