France is ready to launch a military operation in Chad against rebels if necessary, President Nicolas Sarkozy said Tuesday. France has more than 1,000 troops already based in Chad, a former French colony in central Africa where rebels and government troops have been clashing in and near the capital for three days. "If France must do its duty, it will do so," Sarkozy said in response to a question on a possible French military operation in Chad. "Let no one doubt it."

On Monday, the United Nations Security Council paved the way for countries allied with Chad to help repel a rebel offensive.

Sarkozy said French troops not been involved in the fighting except last Friday night, when they opened fire to protect French civilians being evacuated. He said that was a case of self-defense.

Sarkozy dismissed as "absolutely not exact" rebel claims that French forces had killed civilians.

Sarkozy insisted, however, that it would be better to "leave Chad alone."

"If Chad were a victim of an aggression, France would have - and I stress the conditional tense - the means to resist this action."

The fighting appears to have resulted in some civilian casualties and threatened to increase instability in the restive region along the border with war-ravaged Darfur in western Sudan.

A French military spokesman, Christophe Prazuck, said two French soldiers were wounded in the fighting.

Prazuck, speaking on i-Tele television, said the French forces had not "participated in combat" or used aircraft, but had fired shots as convoys sought to bring civilians to camps and airfields.

"We were regularly engaged. We passed under crossfire. We deflected stray bullets, we immediately returned fire, with commensurate force, with infantry weapons," he said.

Prazuck said it was not clear whether the French convoys were specifically targeted by the rebels.

"We had to cross this front to bring our compatriots to military camps. The shots could have come from all sides," he said.