"A French military operation is underway north of Timbuktu. French troops are facing a pretty determined group. At the moment, 19 members of this group have been killed," the Bamako-based source said.
"The French troops haven't reported any deaths or injuries. We are in control of the situation."
A French-led offensive in January drove Islamist groups linked to Al-Qaeda out of the cities of northern Mali, including Timbuktu, Gao and Kidal, after they occupied them in the wake of a coup in Bamako last year.