ADDIS ABABA – Ethiopia has charged its most prominent opposition figure, Jawar Mohammed, and 23 others with terrorism-related offenses, telecom fraud and other crimes, the attorney general’s office announced Saturday. The Oromo make up Ethiopia’s largest ethnic group but had never held the country’s top post until they helped bring Abiy to power. Now ethnic tensions and intercommunal violence are posing a growing challenge to his reforms. His lawyers have repeatedly asserted he was locked up because of his political views and have called for his release. Human rights groups have warned that such arrests show that Abiy’s political reforms are slipping.