Jakarta – An international research group says there is a "slim chance" for peace in the bloody 25-year separatist war in Indonesia's Aceh, but only with sustained international pressure on both sides.

The International Crisis Group (ICG), in a report seen here Thursday, welcomed the outcome of peace talks between Jakarta and the Free Aceh Movement (GAM) in Geneva in February.

"The talks offer a slim chance for peace but there is a need for more persistent and patient international pressure on both sides if the conflict is to be brought to an end," said ICG Indonesia analyst Diarmid O'Sullivan in a statement. "This issue must not be forgotten in the wake of 11 September and the preoccupation with conflicts elsewhere."

The Brussels-based ICG, a private, multinational research organisation, said an estimated 2,000 people were killed last year in Aceh – four-fifths of them being civilians. The report says GAM's power has shrunk since the army launched an offensive in April last year, with only 30-40 percent of the province in Sumatra island under its continuous control compared to 60-70 percent a year ago.

However, "there is little reason to believe the guerrillas can be decisively defeated without inflicting the kind of damage on civilian lives and property that would make renewed rebellion more likely. "At the same time, GAM is far from forcing a government withdrawal. Without a negotiated peace, the war could continue for some time without clear-cut victory for either side."

In the meantime, the ICG says, civilians appear sunk in "disillusionment and despair" amid reports of atrocities by both sides. While the army had worked to improve its image, there were still reports of civilians being killed during patrols or in reprisal for guerrilla attacks. Soldiers and police still extorted bribes at checkpoints. The behaviour of the police mobile brigade Brimob was marked by "brutality and arrogance." The report says parts of GAM "have degenerated into banditry" and the movement as a whole has killed numerous civilians.

At the Geneva talks the two sides agreed to use a special autonomy law passed last July as a basis for negotiations and to end hostilities this year. "However, previous agreements along these lines were violated by both sides, and there is a risk the current round of talks will meet the same fate," the report says. "There is a need for concerted international pressure on both sides to continue talking and to uphold any future agreements..."

The ICG says GAM maintains that some form of autonomy offers the only realistic chance of peace. But it cautions that "corruption is as rife in Aceh as elsewhere in Indonesia, and there is a risk that provincial officials will bend special autonomy to serve their private interests."

For autonomy to work, officials must be more transparent and accountable and the military and police must be willing and able to control abuses. "These conditions are unlikely to be met without wider governance and military reforms in Indonesia," the ICG says. "The international community should be aware that efforts to forge a peace settlement in Aceh and to encourage the gradual reform of the Indonesian state are interlinked and may be mutually reinforcing."