French forces have clashed with rebels in the Central African Republic (CAR) during a government offensive to regain control of the northern town of Birao.
A French army spokesman said troops had reacted in self defence when they came under rebel fire near Birao's airport.
Earlier this month, France promised to provide logistics and intelligence to CAR in their struggle against rebels who have recently seized several towns.
The UN says thousands of people have fled fighting in the region.
The CAR government says it has retaken Birao, 800km (500 miles) north-east of the capital, Bangui, but fighting is reported to be continuing.
Birao is near eastern Chad and Sudan's western Darfur region and has been plagued by violence and insecurity in recent years.
The government says the Union of Democratic Forces for Unity (UFDR) rebels are operating from Darfur with the support of the Sudanese authorities.
French armed forces spokesman Christophe Prazuck said a French military transport plane flew CAR troops to Birao to retake the airport on Monday.
The UN says thousands of people have fled the fighting in the north
"During this operation, the troops were attacked and retaliated. So French troops shot in self defence at rebels who were attacking them," Reuters news agency reports him as saying.
Rebel spokesman Diego Albator Yao has denied that rebels had lost control of the town and said French soldiers were occupying Birao airport.
"Our men are still there, but we don't need to attack the French because they are not interfering in our domestic problem," he told the BBC's Joseph Benamse by phone.
He claimed the rebels had captured another town, Ndele, and were heading for the capital.
Our Bangui correspondent says France recently added 100 troops to its 200 soldiers stationed in CAR.
Under bilateral accords, France's military provides logistical and intelligence support to some of its former colonies in Africa.
The UFDR rebels say they are fighting against corruption and mismanagement under President Francois Bozize, who seized power in a 2003 coup.
The United Nations says 46,000 people have crossed over to neighbouring Chad because of the unrest and another 90,000 are internally displaced within eastern CAR.