Groups of the Ethiopian army and militias attacked Sudanese forces in Al Fashaga, which resulted in death of six soldiers, according to Sudan's army.
Sudan has said "several" soldiers were killed in an attack by armed groups and militias linked to the Ethiopian military in a disputed fertile border region.
Sudanese military sources told Reuters news agency that six soldiers were killed on Saturday in an attack by Ethiopian forces.
"Our forces tasked with securing the harvest in Al Fashaqa... were attacked by groups of Ethiopian army forces and militias, who sought to intimidate farmers and spoil the harvest season," Sudan's armed forces said in a statement.
Sudanese troops "repelled the attack" and "inflicted heavy losses in lives and equipment" on the Ethiopian side, it said.
But the attack left "several killed" among Sudanese forces, the army added.
Ethiopian officials could not be immediately reached for comment.
Relations between Khartoum and Addis Ababa have soured over Al Fashaqa, a border zone long cultivated by Ethiopian farmers but claimed by Sudan.
Al Fashaqa, which also borders Ethiopia's troubled Tigray region, has seen sporadic deadly clashes between the two sides over the past years, but escalated last year.
Tensions rose after fighting erupted in Tigray in November 2020, which sent tens of thousands of refugees fleeing into Sudan.
Khartoum and Addis Ababa have since been locked in a tense war of words over the region, trading accusations of violence and territorial violations.
The border dispute feeds into wider tensions in the region, including over Ethiopia's Blue Nile dam.