Patrick McLoughlin, Stockholm – The leadership of separatist rebels in Indonesia's Aceh province, under attack by government forces after peace talks collapsed, called on the United Nations on Wednesday to intervene immediately in the conflict.

Mahmood Malik, whom the Free Aceh Movement (GAM) movement considers its prime minister, blamed the Indonesian government for breaking off last-ditch weekend talks in Tokyo and said Jakarta had "declared war" on the restive province.

"We condemn the Indonesia government in the strongest terms for destroying all prospects for peace in Aceh ... by launching a military operation," Malik said in a communique.

"We appeal to the United Nations for its immediate involvement in the resolution of the Aceh conflict and for an international fact-finding mission to be sent to Aceh to investigate the crimes against humanity that have been committed."

The Swedish-based leader's calls came after Indonesian troops parachuted into Aceh on Monday in a military offensive aimed at crushing a 27-year-old rebellion that has killed more than 10,000 people, most of them civilians.

Malik also called on countries which supplied arms to Indonesia to prohibit the use of their weapons in the province, which lies on the northern tip of Sumatra.

GAM rebels, who number about 5,000 and demand independence, have estimated 20 civilians have been killed so far in this week's operation. Indonesia's military says it has killed 15 rebels.