French troops have taken control of the airport in the northern Malian town of Kidal, the last rebel stronghold in the north, according to the French army and a local official.
Thierry Burkhard, the French armed forces spokesman, confirmed on Wednesday that French troops were in Kidal and had taken control of the airport.
"The operation is ongoing," he said, declining to give further details.
Separately, Haminy Belco Maiga, president of the regional assembly of Kidal, speaking to Reuters news agency, said: "They arrived late last night and they deployed in four planes and some helicopters."
He said there were no immediate reports of resistance.
Kidal would be the last of northern Mali's major towns to be retaken by French forces after they reached Gao and Timbuktu earlier this week in a campaign to drive al-Qaeda-linked fighters from Mali's north.
France said the area had become a safe haven for fighters.
Kidal is the capital of a desert region with the same name that the fighters are believed to have retreated to during nearly three weeks of French air attacks and an advance by hundreds of ground troops.
Haminy Maiga, the interim president of the Kidal regional assembly, said French forces met no resistance when they arrived late Tuesday.
"The French arrived at 9:30 pm aboard four planes, which landed one after another. Afterwards they took the airport and then entered the town, and there was no combat," said Maiga, who had been in touch with people in the town by satellite phone as all the normal phone networks were down.
"The French are patrolling the town and two helicopters are patrolling overhead," he added.
On Tuesday, a secular Tuareg rebel group had asserted that they were in control of Kidal and other small towns in northern Mali. Maiga said those fighters had left Kidal and were at the entry posts on the roads from Gao and Tessalit.
France, began sending in troops, helicopters and warplanes on January 11 to turn the tide after the armed fighters began encroaching on the south, toward the capital.
French and Malian troops seized Gao during the weekend, welcomed by joyous crowds. They took Timbuktu on Monday. The fighters gave up both cities and retreated into the surrounding desert.
France's president said his country's forces would stay in Mali as long as necessary, but the French also have said they expect troops from African nations to take the lead as soon as they are able.