ADDIS ABABA—The local government in Ethiopia’s Somali region said on Tuesday militia from the neighbouring region of Afar had attacked and looted a town, the latest flare-up in a local boundary dispute that adds to broader tensions in the Horn of Africa nation. Ali Bedel, spokesperson for the Somali region government, said Afar militia “massacred hundreds of civilians” on Saturday in Gedamaytu, also known as Gabraiisa, a town at the centre of long-running regional boundary dispute in northeast Ethiopia. Afar’s government did not immediately respond to requests for comment. However, an internal U.N. report seen by Reuters said there was fighting in Gedamaytu with an unknown number of injured on both sides. Ethiopia has been trying to contain a surge in violence as regions and ethnic groups vie for power and resources. The worst violence, unrelated to the latest flare-up, has been around Tigray in the north, where a conflict …