PARIS — French troops in northern Mali are searching out terrorists who may be mixing among the population in Gao, after new clashes nearby raised questions about how solid a hold the French military has on the strategic city.

French military spokesman Col. Thierry Burkhard said Thursday that the operation to secure Gao is still under way, nearly two weeks after French and Malian troops moved in.

Burkhard said in Paris that there is a risk of "residual presence" of terrorists mixed among the population. Extremists fired rocket launchers at French troops near Gao on Tuesday.

France launched a military operation in Mali on Jan. 11 to help the Malian government restore control. Islamist extremists linked to al-Qaida had imposed severe rule in northern Mali then started pushing toward the capital.