Ethiopian militias raided a Sudanese region along the countries' border, leaving a brigadier general dead.
A senior official at Sudan's eastern border province of Al-Qadarif told Russia Today (RT) that the Sudanese army had launched an "attack and fierce battles along the border with Ethiopia that have left three Sudanese soldiers killed."
The sources stressed that the Sudanese army had recaptured "a number of Sudanese areas which were occupied by Ethiopian farmers in recent days."
Sudan deployed more than 6,000 troops to the border at the start of fighting in Ethiopia's Tigray region that pitted the federal government against regional authorities last month.
Ethiopia's Prime Minister Abiy Ahmed declared victory in the fight. However, clashes between federal and regional forces have continued.
The fighting in Tigray has led to more than 52,000 Ethiopian refugees fleeing to Sudan, mostly in Al-Qadarif.