French and Malian ground forces backed by paratroopers and helicopters took control of Timbuktu's airport and the roads leading to the town in an overnight operation early today.
Colonel Thierry Burkhard said that the town's airport had been taken without firing a shot.
"There was an operation on Timbuktu overnight that allowed us to control access to the town," he said.
"It's up to Malian forces to retake the town now."
French paratroopers swooped in to block any fleeing Islamists while ground troops coming from the south seized the airport, which has been one of the bastions of the fighters who have controlled the north for 10 months.
The airport operation comes a day after the French announced they had seized a key bridge in Gao, one of the other northern provincial capitals that had been in the grip of Islamists.
France's Defence Ministry said a French armoured battalion, along with Malian troops and soldiers from Niger and Chad, were in control of Gao after fighting at the weekend in which "several terrorist groups were destroyed or chased north."
French warplanes had carried out about 20 air strikes at the weekend in the Gao and Timbuktu regions, the ministry added.
The French and Malian forces have met little resistance from the Islamists, who seized northern Mali in the wake of a military coup in the capital Bamako.
During their rule, the Islamists have systematically destroyed Unesco World Heritage sites in Timbuktu.
Islamist fighters torched a library containing historic manuscripts, Mayor Ousmane Halle said.
"It's truly alarming that this has happened," he said.
"They torched all the important ancient manuscripts. The ancient books of geography and science.
"It is the history of Timbuktu, of its people."
In the central Mali town of Konna, where France opened its offensive 17 days ago, local people showed journalists the graves of civilians killed in the air strikes.
Konna Deputy Mayor Demba Samouka insisted that there was no precise death toll available, but said at most four civilians had died in the air raids, blaming other civilian deaths on Islamist fighters.
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