Rival armed groups in northern Mali clashed in Anefis town over the weekend, leaving 15 fighters of the rebel group Coordination of Azawad Movement (CMA) dead.
The fighting was the first apparent breach of a peace agreement between the armed groups signed with the government in June, Xinhua reported.
Eyewitnesses said several CMA vehicles were burnt and two of the group's leaders were "taken into custody".
The UN Peacekeeping Mission in Mali (MINUSMA) condemned the clashes and vowed to take actions to protect the endangered civilians.