Ethiopia says it has thwarted a planned attack by an Eritrea-backed group on its massive dam project, the Grand Ethiopian Renaissance Dam.
Deputy government spokesman Zadig Abraha told the state-affiliated Fana Broadcasting Corporate on Wednesday evening that 20 members of the armed group were "completely annihilated" earlier this week.
Zadig says "actions were taken" against 13 members of the Benishangul Peoples Liberation Movement. The spokesman did not give details, but similar statements have meant people were killed.
The spokesman says the other members escaped to Sudan, which then handed them over.
Ethiopia's dam project is about halfway complete and has been a source of regional tension. Egypt has long suspected it will reduce its share of the Nile River.
Ethiopia and neighboring Eritrea have a long history of border disputes.