Darfur rebels opposed to a recent peace deal in Sudan's Darfur region have fought with government soldiers near Sudan's border with Chad.
Few details of Saturday's battle could be confirmed, but aid workers say wounded fighters are being treated at a hospital in eastern Chad.
The fighting was between Sudanese troops and Darfur's Justice and Equality Movement.
The Justice and Equality Movement is part of a new rebel alliance called the National Redemption Front. The group, along with a faction of the Sudan Liberation movement, rejected a peace deal with the government in May.
The United Nations recently approved a plan to absorb and expand an African Union force that has been unable to control violence in the Darfur region.
Sudan has said it would accept U.N. logistical support for the A.U. mission. But it has rejected the proposed U.N. takeover of the force, likening that move to colonization.
More than three years of fighting in Darfur has killed an estimated 200,000 people and displaced two million others from their homes.