"The first talk last night, as we expected, was tough," Yusuf Kalla told reporters after attending a political party meeting in Jakarta.

Kalla said the two sides were still on course for a second round of dialogue later Saturday.

"It is tough, but still going on," he said.

The talks in a snowbound manor house near Helsinki are aimed at formalising a ceasefire between the rebels and Indonesian military to safeguard relief efforts in the province which bore the brunt of last month's tsunami disaster.

In their first contact since a truce collapsed 20 months ago prompting a military offensive, the government has offered autonomy and amnesties to the rebels but rejected any bid for sovereignty.

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