Military officials in Congo Brazzaville say there've been fierce clashes over the past few days in the areas of Ganga-Lingolo and Linzolo, south of Brazzaville.

They say the fighting began on Monday when rebel forces, known as Ninjas, attacked an army convoy.

Troops loyal to President Denis Sassou Nguesso then fired mortar rounds into the surrounding hills where the rebels were believed to have taken refuge.

There's no independent confirmation of the army account.