Witnesses in Chad say rebel forces have attacked government forces in the eastern city of Abeche this Saturday morning.
Abeche is located several hundred kilometers east of the Chadian capital of N'Djamena. Further details of the situation in the city were not available.
Earlier this week, the Chadian government extended emergency measures by six months in order to quell ethnic conflicts in the country's east. The emergency was imposed after fighting broke out between ethnic Arab and ethnic African communities, killing at least 400 people.
U.N. officials say Chadian villagers have reported being attacked by Arab nomads from Chad and western Sudan. The attacks have raised fears that the violence in Sudan's troubled Darfur region is spilling over into Chad.
N'Djamena has accused Khartoum of supporting the nomads, an accusation Sudan denies.
Eastern Chad is home to more than 200-thousand refugees from the war-torn Darfur region of neighboring Sudan. The U.N. also says more 90,000 people in have been displaced in the region, including 15,000 since the beginning of November near the border with Darfur.
Some information for this report was provided by AFP and AP.