France's La Croix daily, citing diplomats and military sources, said members of the special operations command (COS) helped to drive back rebels in fighting around the capital N'Djamena.

"No special force or French soldier took part in fighting between government forces and rebel forces," said General Christian Baptiste, a Defence Ministry spokesman.

The newspaper said French soldiers also opened fire on rebels approaching the airport during an evacuation of foreigners.

"They did carry out protection operations for French citizens but also from the international community. They had to extract from the fighting zone a certain number of citizens and diplomats from the international community and they helped those who wanted to leave Chad by military plane," Baptiste said.

Chadian President Idriss Deby, speaking on French radio on Thursday, said he had never lost control of his country and France had not directly intervened in the fighting.

He has called on the European Union to deploy a peacekeeping force urgently in eastern Chad after the rebel assault.

The rebels say they have been bombed by warplanes belonging to France, the former colonial power which has more than 1,000 troops stationed in the central African oil producer.

Relations between the two countries were strained in October when Chad arrested six French aid workers for trying to kidnap 103 local children, who they were attempting to take to Europe for fostering without permission from the authorities.

The aid workers were jailed in Chad but transferred to France to serve most of their 8-year sentences in French prisons.

In a sign that relations have improved since French President Nicolas Sarkozy threw his support behind Deby, the Chadian president said this week he would be prepared to pardon the aid workers if France requested it.

France has said each of the six has asked for a pardon. Junior foreign minister Rama Yade said the ministry would pass on these requests to Chad on Friday.

RTL radio said that five of the workers were likely to be released but the group's leader, Eric Breteau, might have to stay in jail but serve a reduced sentence.

"Maybe it's not final, maybe Sarkozy can help Deby to change his mind," Breteau's mother Helene told RTL. "I'm still hoping."