The French and US embassies in Chad were preparing their nationals there for possible evacuation on Saturday as advancing rebels opposed to President Idriss Deby threatened the capital N'Djamena from the northeast.

France's mission instructed its citizens to assemble at three designated sites in the capital, while the US embassy asked those American nationals who wanted to be evacuated to come to the embassy immediately.

Radio France International reported that the sounds of heavy weapons fire could be heard coming from outside the city from the northeast, where government troops had fought on Friday to try to halt a determined rebel advance on the capital.

A Chadian opposition Web site reported that the rebels, who have called on Deby to accept a power-sharing deal or face an attack on N'Djamena, had occupied Djermaya, 30 km from the capital, and were pressing on towards the city.

But there was no immediate independent confirmation of this. Chad says the rebels, who advanced rapidly to N'Djamena in the west after crossing from the eastern border with Sudan's war-torn Darfur region, were armed and backed by the Sudanese government.

Khartoum routinely denies such accusations. Both sides claimed victory in Friday's confused fighting. It was the rebels' most threatening advance on N'Djamena since 2006, when government troops drove out a rebel column that entered the city.

France on Friday reinforced its military contingent stationed in its former colony, and the clashes outside the capital forced the European Union to delay the deployment of a peacekeeping force in eastern Chad.-Reuters