The International Committee of the Red Cross last week said that more than 60 people were treated for conflict-related injuries following clashes in Jonglei in South Sudan.
South Sudanese army Gen. Peter Gadet Yaak said his forces captured an airbase used by rebel forces allegedly getting support from Sudan, the independent Sudan Tribune reports.
Sudan and South Sudan agreed recently to pull forces away from the border and set up a demilitarized zone. Border conflicts are among the issues threatening a fragile peace agreement that secured South Sudan's independence in 2011.
"We have captured the areas of military power from the rebel forces together with their airfields," Yaak said.
U.N. special envoy Hilde Johnson told the U.N. Security Council in March that violence in Jonglei, South Sudan's largest state, is a "major concern" for the U.N. Mission in South Sudan.
She said South Sudan was committed to finding a peaceful solution but warned time was running out.