French troops have secured the northern Malian town of Kidal, the last rebel stronghold in the region, according to military officials.
Many fear the fighters, who have reportedly already left the town near the Algerian border, now will attempt to hide in the surrounding mountains, only to return and attack the weaker African forces once the French are gone.
Wednesday's capture of Kidal came just days after French and Malian forces retook two other provincial capitals, 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.
Haminy Belco Maiga, president of the regional assembly of Kidal, said French troops had met no resistance.
"The French arrived at 9:30pm 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.
Earlier, French Defence Minister Jean-Yves Le Drian said a sandstorm had delayed the troops from leaving the airport.
"Nobody questions France's rapid deployment but the ability to hold on to the cities and territory is an immense challenge. It is not clear how they will be able to sustain the recent gains,'' said Alex Vines, head of the Africa programme at Chatham House.
"The Islamist extremists have not been defeated; they have melted into the heat haze of the desert.''
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.
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.
"The French see their role now as winding down," Rowland said. "Their role was to push back the rebel offensive and to retake the key towns - the last part of the mission to hold the territory and to re-establish Mali as a sovereign integral state."
Meanwhile, a group of Chadian soldiers left their temporary base in Niamey on Wednesday, as their convoy rolled through the town of Gorou, Niger and towards the country's northern border to enter Mali.
The troops are part of a larger African force known as AFISMA, which is due to send more than 8,000 soldiers to Mali to aid in the country's fight against such groups.
The bulk of the planned African intervention force for Mali is still struggling to get into the country, hampered by shortages of kit and supplies and lack of airlift capacity.
Around 2,000 AFISMA troops are already on the ground to fight the rebels, who have retreated to the rugged northeast mountains of the Adrar des Ifoghas range on the border with Algeria.