Indonesian police have arrested four rebel members of a joint committee established to monitor a ceasefire in the province of Aceh.

The four members represented the separatist Free Aceh Movement (GAM) on the Joint Security Committee. The committee was set up to monitor the December 9 peace deal between the GAM and the Indonesian government.

GAM committee member, Nashiruddin Ahmed, says police arrested his four colleagues at the Banda Aceh airport as they prepared to fly to Jakarta. He says he does not know why the delegates have been detained. The committee also includes delegates from the Indonesian government and the European-based Henry Dunant Centre.

The truce is on the brink of collapse and the military is preparing for a possible offensive. The United States, European Union and Japan have urged Indonesia not to launch a military operation in Aceh, and have called on the GAM to declare unconditional support for a peaceful solution.