Jakarta – Talks to end a separatist rebellion in Aceh Province are stirring hopes for peace after three decades of violence, but experts say the optimism looks misplaced.

They cited decades of mutual mistrust, the sensitive issue of rebel disarmament and the possible withdrawal of Indonesian troops as issues that could derail enforcement of a deal even if one were signed in coming months to end the insurgency, one of Asia's longest.

Government negotiators and rebels of the Free Aceh Movement, along with their Finnish mediators, voiced confidence in Helsinki on Tuesday that the next round of talks would lead to an end to the three-decade war, which has killed 12,000 people in Aceh.

"I can understand why people are trying to talk it up," said Edward Aspinall, a Southeast Asian studies lecturer at Sydney University and an expert on Aceh. "But given the past experiences, there are just so many potential stumbling blocks.

"Even presuming an agreement can be reached on the political and security issues, then the question of actually managing that incredibly fractured and complex scene on the ground will be very great I think."

A fifth round of talks will be held in the Finnish capital from July 12 under the auspices of a former Finnish president, Martti Ahtisaari. On Tuesday, Ahtisaari hinted he had set aside a date in August for a signing ceremony.

Peace talks were revived in January after tsunamis crashed into Aceh on Dec. 26, killing up to 160,000 people in the province, which is on the northern tip of Sumatra Island.

The Indonesian government and legislators will study rebel documents that contain the positions of both sides on issues including political participation and a cease-fire.

While it is unclear what these documents contain, Teuku Muhammad Nurlif, an Acehnese legislator from the Golkar Party, the biggest in the Indonesian Parliament, said the rebels would not be allowed to contest elections as a local party.

During the third round of negotiations in April, the rebels proposed changes to Indonesian laws that stipulate parties must be nationally based, with branch representation in more than half of Indonesia's provinces and their headquarters in Jakarta.

The Indonesian information minister and negotiator, Sofyan Djalil, had already rejected this before the May talks, reflecting Jakarta's anxiety about keeping the diverse country together, and not allowing local parties based on ethnicity or language.

Andi Widjajanto, a military analyst at the University of Indonesia, said Parliament would also not accept any deal unless the rebels handed in all their weapons, which could prove tricky.

"The strategy seems to be let's agree first in resolving the conflict while the details can be talked about later," he said. "The details will either make or break this agreement."

In earlier rounds, the rebels made a significant concession by dropping their demands for independence in exchange for "self-government" for Aceh with locally based political parties. But Jakarta, publicly at least, appeared unwilling to bend much, Aspinall said.