The airport in Gao – seized by an alliance of Tuareg rebels and Islamists last April – has been secured along with the strategic Wabary bridge over the Niger River, the French Defence Ministry said.
French special forces were said to be confronting harassment from rebel fighters after they melted in to the local population.
French and Malian troops have advanced rapidly against al-Qaeda-allied Islamist militant fighters holding the Saharan north of the West African state after France intervened earlier this month at the request of the Malian government.
In a statement yesterday, French Defence Minister Jean-Yves Le Drian said 3700 French troops were engaged in Operation Serval, 2500 of them on Malian soil. The UN refugee agency says more than 7000 civilians have fled to neighbouring states since January 10 to escape the fighting.
For two weeks, French jets and helicopter gunships have been harrying the retreating Islamists, destroying their vehicles, command posts and weapons depots. The action had already halted an Islamist offensive launched earlier this month that threatened Mali's southern capital, Bamako.
France launched its military operation on January 11 after its ambassador to Mali sent an urgent message to Paris, warning that if the strategic city of Mopti fell to armed Islamic militants, there would be nothing to stop them from capturing the capital, Bamako, and controlling the entire country.
However, the military intervention has revived trans-Atlantic tensions over security issues, and prompted criticism from those who see US President Barack Obama as too reluctant to use military force.
Officials from both sides have said the French have privately complained about what they see as paltry and belated American military support for their troop deployment,
French President François Hollande called Obama on January 10 and in a brief conversation about Mali, told the US president France was about to mount a major military operation in its former colony.
However, France's sense of urgency has prompted American concerns about whether Paris has a long-term plan for Mali, whether the French have thought through an exit strategy, and about getting the US military deeply involved in a new foreign conflict as Obama begins his second term in office.
The US has given significant intelligence support to French forces in Mali, and has helped to airlift French troops and equipment into the country, according to US officials. The UK is providing the French with logistical and surveillance support.
France wants more US and European help to move its soldiers and materials and help with refuelling for planes to assist with airstrikes.
The UN Security Council last month authorized deployment of a 3300-member African military force, known as AFISMA, to Mali.
The full force was not expected to be ready until at least September, but it now appears the deployment will be sharply accelerated.
France has not specified how long its troops will stay in Mali, where they hope to split local Tuareg rebels away from AQIM (al-Qaeda in the Islamic Maghreb) militants and into talks with the Malian government.
But a senior French official said: "The longer we stay, the bigger the risks."