The announcement has reversed France's earlier stance that it would only provide air and logistical support for a military intervention led by the African troops.
France, the former colonial power in Mali, has committed about 1,700 troops and air crews to the fight, Le Drian was quoted as saying by CNN. The force includes about 800 troops on the ground in Mali, including an armor unit.
"Now we're on the ground. We will be in direct combat within hours." French Military Chief of Staff Admiral Edouard Guillaud said Wednesday morning.
French President Francois Hollande said Tuesday that its military intervention in Mali would end only when the Islamist militant groups were wiped out and political stability was restored.
France had no intention of staying in Mali permanently but would do what was necessary until the African force was ready to take over, he said.
Hollande denied suggestions that the military intervention served France’s economic interests.
“This has nothing to do with the practices of another era,” he said at a press conference in Dubai. “France has no other interests to defend in Mali. What companies?” he asked.
"If we had not taken up our responsibility and if on Friday morning we had not acted with this intervention, where would Mali be today?" he questioned.
French troops arrived in Mali Friday, flying in from the bases in Ivory Coast and Chad, to fight Islamist insurgents, in an operation backed by the U.N., the E.U. and the U.S.
"Our action will last however long is necessary," Hollande said in a television address Friday night. "France will always be ready to defend the rights of a people which wishes to live in freedom and democracy.”
Fighting between the Malian government forces and the Tuareg rebels broke out in the country’s north in January last year, and the country descended into chaos in March when soldiers toppled President Amadou Toumani Toure in a coup d’état.
The security vacuum that followed led to the rebels seizing control of two-thirds of the country. The political instability and fighting have driven 500,000 Malians from their homes, 270,000 of them to neighboring countries, according to an U.N. estimate.
Western nations fear that the insurgents, with the support from Al-Qaeda in the Islamic Maghreb, could use Mali as a base for unleashing terror on the West and expand the influence of Islamist militants in Yemen, Somalia and North Africa.
Meanwhile, Somali militants said that they had decided to execute a French intelligence agent they have held for more than three years, days after a French commando raid Friday to rescue him failed.
The al-Qaeda linked al-Shabab said in a statement Wednesday that they "reached a unanimous decision to execute the French intelligence officer, Denis Allex,” the AFP reported.
A senior militant official confirmed to the AFP that Allex "has been sentenced and this judgment will not be changed. As far as we are concerned this man should die.”
Responding to the statement, Guillard told Europe 1 Radio that the French authorities did not have any proof since the rescue attempt that the hostage was alive.
"We have nothing since Friday's raid on Denis Allex being alive. We think he is likely dead," Guillard was quoted as saying by Reuters.
Two French soldiers had died in the botched rescue attempt.