The defence ministry in Mali says 20 people were killed in an attack by Tuarag rebels on an army barracks in the north of the country.
It's the first major clash since a peace deal was signed in July.
Military sources said a rebel column of more than 20 vehicles had raided the town of Nampala.
The fighting came days after Mali's president Amadou Toumani Toure reiterated his call for further peace talks.
The Tuaregs want more resources to be spent in their homeland in the Sahara desert, in northern Mali.