France's defence ministry confirmed four Rafale fighter jets flew from France for the third day of air strikes and hit rebel training camps, depots and infrastructure.
The attack on Gao, the largest city in the vast territory seized by Islamist rebels in April, marked a decisive drive northwards.
France is determined to end Islamist domination of northern Mali. Many fear it could be a base for attacks on the West and link up with al Qaeda elsewhere.
France's Defence Minister Jean-Yves Le Drian said French intervention on Friday stopped rebels seizing Bamako itself. He said air raids would continue in the coming days.
"The President is totally determined we must eradicate these terrorists who threaten the security of Mali, our own country and Europe," he told French television.
In Gao, where Islamists have imposed an extreme form of Sharia law, residents said French fighters and helicopters pounded the airport and rebel positions. A huge cloud of black smoke rose from the militants' camp.
Resident Soumaila Maiga said by telephone: "We are happy, even though it is frightening. Soon we will be delivered."
Malian rebels said the French had also bombed targets in the towns of Lere and Douentza.
France has deployed 550 soldiers to Mali, with 100 seen arriving by plane yesterday. In Bamako, cars had French flags draped from the windows to celebrate Paris's intervention.
More than 20 years of peaceful elections earned Mali a reputation for democracy, but the image unravelled after a military coup last March left a power vacuum for the Islamist rebellion. French President Francois Hollande's intervention in Mali has won plaudits from other leaders but is not without risks.
It raised the danger level for eight French hostages held by al Qaeda in the Sahara, and for 30,000 French citizens in Muslim neighbouring states. France has tightened security on public buildings and advised its 6000 citizens in Mali to leave after Islamists promised revenge.
In its first casualty of the campaign, a French pilot was killed on Friday when rebels shot down his helicopter.
Hours earlier, a French intelligence officer held in Somalia by Islamist extremists died in a botched raid to free him.
President Hollande says France's aim is to support a UN-backed mission by West African bloc ECOWAS to retake the north.
Ivory Coast President Alassane Ouattara, currently ECOWAS chairman, convened a summit of the 15-nation bloc on Saturday to discuss the mission.
An Ivory Coast minister later said African troops would arrive in Bamako yesterday and today.
There are fears, though, the African states have neither the equipment nor the troops for the intervention.
Britain, the US and Canada have promised logistical support.