Jakarta: A former top Indonesian state intelligence official went on trial on Thursday for allegedly ordering the murder of the country's most prominent human rights activist four years ago.

Retired army General Muchdi Purwoprandjono, 59, was arrested in June on charges of involvement in the poisoning of Munir Thalib, who died of an arsenic overdose in September 2004 while flying from Jakarta to Amsterdam aboard the state airline, Garuda.

Purwoprandjono could face a death sentence if found guilty of ordering the murder.

Possible motive

Thursday  prosecutors said they had uncovered a possible motive in the case.

Prosecutor Cyrus Sinaga told a packed courtroom the defendant had "ordered Munir be killed" because he had exposed Purwoprandjono's involvement in the abduction of 13 activists that led to his firing.

"The defendant hated Munir because he was sacked after just 52 days as commander of the Kopassus [Special Forces]," Sinaga said.

Defence lawyer Lutfi Hakim dismissed the accusation as "absurd," arguing that prosecutors had based their case "on assumptions instead of facts."

Purwoprandjono's trial at the South Jakarta District Court marks a giant leap in the investigation of Thalib's killing, long undermined by high-level corruption.

"I just hope that at this trial Muchdi will dare to reveal who actually ordered him," said Thalib's widow, Suciwati, who has long alleged her husband was the victim of a state-sponsored conspiracy.

Observers see the proceedings as an important gauge of progress in human rights and judicial reform in Indonesia since the end of the 32-year Suharto dictatorship a decade ago.

Purwoprandjono is the first official at the State Intelligence Agency to be linked to a plot to have Thalib killed and could implicate other authorities.

Thalib gained fame and made many powerful enemies for exposing abuses by the Indonesian army during Suharto's rule.

In January, the Supreme Court sentenced Pollycarpus Budihari Priyanto, a 46-year-old pilot, to 20 years in prison for carrying out the murder.