Jakarta – Two international human rights bodies yesterday dismissed as "seriously flawed" the just-concluded trial of 24 Indonesian soldiers and a civilian for a massacre in Aceh province, saying it had missed the real culprits in the slaughter.

Military commanders and not just their troops should have been held accountable for the massacre of more than 50 people last year, the London-based Amnesty International and New York-based Human Rights Watch said in a joint statement.

The groups expressed "serious misgivings" over the sentencing on Wednesday of 24 soldiers and a civilian to up to 10 years' jail for the killings last year of Teungku Bantaqiah and 57 of his followers. The flaws in the trial could make it seem only a "public relations exercise" in the eyes of the Acehnese people.

"The trial shows the Indonesian Government's resolve to put an end to military impunity in Aceh, and that is an important step forward," the joint statement said. "But it is a seriously flawed beginning. Commanding officers were not charged and key witnesses failed to appear."

None of the accused in the trial was "above the rank of captain and the majority were privates or non-commissioned officers". The accused troops' commanding officer, Lieutenant-Colonel Sujono – who had been named as one of the accused – has disappeared.

Another senior officer, Lieutenant-Colonel Syafrul Armen, who appeared as a witness, "admitted to having ordered troops to bring back Teungku Bantaqiah dead or alive and was not charged".

Wednesday's sentencing of the 25 by a joint civilian-military tribunal was considered a big step by authorities in addressing gross human rights abuses in Aceh, where troops and members of the separatist Free Aceh Movement have been fighting for more than two decades.

Amnesty and Human Rights Watch said the trial lacked credibility and legitimacy because of the lack of charges against senior officers, an argument also used by the defence lawyers during the trial and protesters who picketed the courthouse during several of its sessions.

"If the justice effort in Aceh is to be credible, the most senior culpable officers must be brought to justice," the statement said. "The exclusive focus on junior ranks weakened the legitimacy of the trial among Acehnese observers and among observers elsewhere in Indonesia. It suggests that the Government is still unwilling or unable to take decisive action against higher level military leaders."

The statement also said the non-appearance of some witnesses appeared to be because they had not been called or were afraid because of the lack of a witness protection program. "In Aceh, where the security forces have ... a long record of literally getting away with murder, the potential for intimidation is high," the statement said.

The statement warned that if the massacre trial was a "foretaste" of how Indonesian authorities planned to conduct trials into the post-ballot violence in East Timor last year, "it does not bode well".

The UN Commission on Human Rights has urged that an international war crimes court be convened to try those responsible for the wave of violence in East Timor carried out by Indonesian military-backed militia.

But the commission has said it is waiting first to see whether Indonesia conducts a credible legal process and brings those responsible to justice.