Four Ethiopian UN peacekeeping troops have been killed by a landmine in Sudan's disputed region of Abyei. A UN spokesman said seven other peacekeepers were injured by the blast in Mabok, south-east of Abyei town, which was occupied by northern forces. UN Secretary General Ban Ki-moon was "saddened" by the deaths, he added. The deaths come less than a week after the 4,200-strong Ethiopian peacekeeping force arrived in Abyei, claimed by the governments of Sudan and South Sudan. UN spokesman Martin Nesirky said Mr Ban had expressed his condolences to the Ethiopian government, and the family and friends of those killed. The injured have been airlifted to Kadugli, in the Sudanese state of South Kordofan. The village where the landmine exploded had been occupied by troops loyal to the government in Khartoum, which has signed the Ottawa Treaty banning the use of anti-personnel mines. Buffer zone Northern forces had occupied Abyei in May, raising fears of a renewal of Sudan's 21-year, north-south conflict. After the offensive, more than 100,000 people fled the territory, mainly to South Sudan, which gained independence on 9 July. But in June, both north and south agreed to withdraw their troops from Abyei, leaving a 20km (12-mile) buffer zone along the border. A week later, the UN Security Council voted unanimously to send a 4,200-strong Ethiopian peacekeeping force to Abyei to monitor the withdrawal, as well as human rights. The resolution established a new UN peacekeeping force, the United Nations Interim Security Force for Abyei (Unisfa). It also ordered Unisfa to protect civilians and to "protect the Abyei area from incursions by unauthorised elements". Sudan's permanent representative to the UN, Daffa-Alla Elhag Ali Osman, said northern forces would withdraw as soon as the Ethiopian troops had been deployed. Source: BBC