New York – US-based rights groups called for a UN inquiry to bring to justice Indonesian security officers let off the hook for atrocities during East Timor's 1999 violence-marred independence vote.

An Indonesian appeals court had overturned the convictions of four high-ranking Indonesian security officials and halved the 10-year sentence of a notorious pro-Jakarta militiaman who oversaw the murder and torture of independence supporters.

"The decisions show that courts in Indonesia are simply not independent and are incapable of rendering justice for the atrocities committed in East Timor," said Brad Adams, executive director of Human Rights Watch's Asia Division.

All four security officials had been earlier found guilty of crimes against humanity by the ad hoc Human Rights Court in Jakarta, which Indonesia created in an attempt to shield itself from calls for an international tribunal.

"Indonesia has given the international community no choice but to initiate a justice mechanism for these appalling crimes, which took place in full view of the world in 1999," Adams said.

He said the United Nations should take steps to create a judicial process that would bring to justice those responsible for these crimes. The support of the United States, Japan, Australia, and European Union countries was essential in this effort, he said.

In a recent letter to UN Secretary-General Kofi Annan, Human Rights Watch and other human rights groups urged the world body to immediately establish a Commission of Experts "to resolve the impunity gap created by the Indonesian ad hoc Court in Jakarta."

The East Timor Action Network (ETAN), which had been calling for an international tribunal to prosecute crimes against humanity in East Timor since 1975, also sought the intervention of the United Nations in the case.

"Now that Indonesia's judicial farce is in its final act, the United Nations must step in and create an international tribunal with the resources and clout to credibly prosecute the masterminds of the terror in East Timor," ETAN spokesman John Miller said Friday.

He urged the US administration and Congress to strengthen restrictions on assistance to the Indonesian military "until there is meaningful justice."

East Timor, which won full autonomy in 2002, has downplayed the importance of the trials, insisting that forging good ties with Indonesia is a greater priority.

Indonesia invaded East Timor in December 1975, shortly after Dili declared independence from centuries of Portuguese colonial rule.