Islamist insurgents have launched a surprise raid in the heart of the Malian town of Gao, battling French and local troops in a blow to efforts to secure Mali's recaptured north.
Local residents hid in their homes or crouched behind walls as gunfire from running street battles resounded through the town retaken from Islamist rebels last month by a French-led offensive.
French helicopters fired on al-Qaeda-allied rebels who had infiltrated the central market area and a police station, Malian and French officers said.
After driving the bulk of the insurgents from major northern towns such as Timbuktu and Gao, French forces are trying to search out their bases in the remote and rugged Adrar des Ifoghas mountains, far up in the northeast.
"They infiltrated the town via the river. We think there were about 10 of them. They were identified by the population and they went into the police station," said General Bernard Barrera, commander of French ground operations in Mali.
He told reporters in Gao that French helicopters had intervened to help Malian troops pinned down by the rebels, who threw grenades from rooftops.
Malian gendarme Colonel Saliou Maiga told Reuters the insurgents intended to carry out suicide attacks in the town.
No casualty toll was immediately available. Malian soldiers said some of the raiders may have come on motorbikes.
Abdoul Abdoulaye Sidibe, a Malian parliamentarian from Gao, said the rebel infiltrators were from the MUJWA group that had held the town until French forces liberated it late last month.
MUJWA is a splinter faction of al-Qaeda's North African wing AQIM which, in loose alliance with the home-grown Malian Islamist group Ansar Dine, held Mali's main northern urban areas for 10 months until the French offensive drove them out.