"Negotiations will continue Saturday, and we hope that the talks can continue in the same constructive spirit as on Friday," Maria-Elena Cowell, a spokeswoman for the Crisis Management Initiative foundation (CMI) hosting the talks in the Finnish capital, told AFP.

Leaders of the separatist Free Aceh Movement, GAM, and an Indonesian delegation headed by three government ministers arrived in Helsinki on Thursday, initially meeting separately with former Finnish president Martti Ahtisaari, who heads CMI and is mediating the talks.

On Friday, the two parties met face-to-face for the first time since a truce between them broke down and the government in May 2003 declared martial law and launched a major military offensive in the province

"The first talk last night, as we expected, was tough," Indonesian vice president Yusuf Kalla told reporters in Jakarta early Saturday, adding that the government would carry on peace negotiations.

Jakarta has offered autonomy and amnesties to the rebels but rejected any bid for sovereignty.

The meetings, shrouded in secrecy, were held at Koenigstedt Manor, a baronial estate used by the Finnish government for representative purposes, some 24 kilometers (15 miles) north of Helsinki and near the capital's airport.

"Issues have covered the humanitarian catastrophe in the region and the post-tsunami reconstruction," Cowell said.

The talks were prompted by a recognition that peace was needed in the province to carry out relief work there after it was devastated by gigantic waves triggered by a sub-sea earthquake on December 26, killing some 230,000 people.

The tsunami wiped out whole communities in Aceh, leaving many more without shelter, food and basic sanitation, and a huge international emergency operation is now taking place there to relieve the situation.

GAM has since 1976 been fighting to win independence for Aceh, located in the north of the Sumatra island, claming that Jakarta is syphoning off the province's rich oil and natural gas resources.

Following the tsunami disaster, both the government and rebels called for a formal ceasefire in order to facilitate the ongoing massive relief effort.

Despite upbeat signals from organizers following Friday's talks, few observers expect the Helsinki deliberations to go beyond formalizing a month-long cessation of hostilities.

Ahtisaari, who was president of Finland from 1994 to 2000, is a former career diplomat and under-secretary general of the United Nations.