Rebels in Sudan's western Darfur region ambushed a small army unit Friday, triggering an hours-long clash that killed 21 people, including 13 rebel fighters, the military said.
Army spokesman Capt. Sawarmy Khaled said the rebels behind Friday's attack were led by the main Justice and Equality Movement, which has been involved in faltering peace talks with the government.
The fighting took place on a main north-south highway in the vast desert region, he said in remarks carried by the Sudan News Agency.
The Darfur conflict began in 2003. As many has 300,000 people have died in the fighting between forces from the Arab-led central government and rebel factions whose demands include greater control over natural resources.
At least 2.7 million people have been displaced inside Darfur and in neighboring Chad.
More than two years of talks in Qatar under the mediation of the Gulf state's leaders have failed to reach a comprehensive peace deal.
Fighting flared in December, and the government walked out of the talks in Qatar. Mediators, however, have said the peace talks are not dead and that shuttle diplomacy between rebel groups and the government are taking place.
Khaled said the military was carrying out what he described as a wide-ranging mopping-up operation in search of the remnants of Friday's attacking forces.
Several of the rebel group's spokesmen could not be reached for comment Friday night.