Pressure was mounting on Indonesia to address its bloodstained exit from East Timor in 1999, as a UN team of experts called for an international tribunal to prosecute security forces and militia.
The report by the UN Commission of Experts panel is the latest in a series of harsh assessments of Jakarta's effort to examine atrocities in East Timor, which wound up last year having failed to jail any senior officials.
In its report, a copy of which was seen by AFP, the experts said Indonesia's ad hoc human rights court was "manifestly inadequate" and "shows scant respect for or conformity to relevant international standards". The three-member panel recommended that the UN Secretary General require Indonesia to account for its prosecutions within six months or allow an international tribunal to bring those responsible for the violence to justice.
Pro-Indonesian militia gangs, allegedly directed by Indonesian army officers, went on a rampage before and after East Timorese voted for independence from Jakarta in a UN-sponsored ballot in August 1999.
They killed about 1,400 independence supporters in the former Portuguese colony, laid waste to much of the infrastructure and forcibly deported 250,000 people after the poll resulted in an overwhelming vote for separation.
Human rights trials held in Indonesia to try those responsible – and deflect UN calls for a proper tribunal – ended last year after acquitting all but one of the 18 security officers and officials who appeared before them.
The UN Commission's report prompted a call from the New York-based Human Rights Watch for the United Nations Security Council to endorse the recommendation.
"The Security Council should make it clear that it will establish an international tribunal if Indonesia does not seriously pursue justice," said Brad Adams, Asia director at Human Rights Watch.
"The UN experts' report shows the Security Council that it's time to put its weight behind a credible justice process," Adams said, describing the Indonesian human rights court as a sham.
Indonesian foreign ministry officials could not be reached for comment on the report.
The UN commission visited Indonesia in May to assess the country's efforts after earlier visiting East Timor to review the work of a parallel prosecution body tasked with indicting human rights violators.
Jakarta had argued that the United Nations panel was redundant in light of the creation of a joint reconciliation panel with East Timor, called the Commission of Truth and Friendship, but later agreed to cooperate.
But the UN experts said some aspects of the reconciliation body's brief "contradict international standards on denial of impunity for serious crimes".
East Timor leaders have said they do not support an international tribunal, preferring to focus on good ties with the tiny state's giant neighbour.
Indonesia's Foreign Minister Hassan Wirayuda said last month that the country's human rights tribunal was "imperfect" but stressed both Jakarta and Dili were "trying to move forward".
East Timor gained full independence in May 2002 after more than two years of UN stewardship.