U.N. Secretary-General Ban Ki-moon on Wednesday named a new special representative in Mali where the peacekeeping mission has struggled to help implement a peace deal amid a surge in violence by militants. Ban named Mahamat Saleh Annadif, the former foreign minister of Chad, to head the 10,000-strong MINUSMA force, which has suffered the highest rate of losses of any active peacekeeping mission, according to a statement. He replaces Mongi Hamdi of Tunisia, who will complete his assignment next month. Militants linked to al-Qaeda seized Mali's desert north in 2012. They were scattered by a French military intervention the following year, but fighters have stepped up attacks this year, hitting targets beyond their traditional northern bases. In November, militants attacked a luxury hotel in the capital Bamako and killed 19 people, including many foreigners. Earlier this month, rockets hit a U.N. base in Kidal, killing three people.