MOGADISHU - Somalia's militant Islamist group al Shabaab seized a town in the south of the country early on Friday after it was abandoned by the military and African Union-mandated (AMISOM) peacekeepers, residents said.The town of Leego, which lies about 130 km (80 miles) to the northwest of the capital Mogadishu, is in Somalia's lower Shabelle region where al Shabaab last week killed at least 12 peacekeepers in one of the deadliest attacks on AMISOM.Farah Ahmed, a resident of Leego, told Reuters AMISOM and Somali military forces had pulled out of the town early on Friday."That same minute al Shabaab entered to control the town... The town is now calm and al Shabaab fighters are in every part of the town."It was not immediately clear why the military and AMISOM had withdrawn from Leego."The town (Leego) is now under our control," Sheikh Abdiasis Abu Musab, al Shabaab’s military operations spokesman, told Reuters by telephone.Al Shabaab is fighting to topple Somalia's Western-backed central government and to rule the Horn of Africa country according to its strict interpretation of Islamic sharia law.The group was ejected from Mogadishu in 2011 and has since been chased from most of its other strongholds across the country.But it remains a formidable threat, with its fighters frequently carrying out bombings against both civilian and military targets in Mogadishu and other towns in Somalia.The militants also conduct regular attacks across the border into neighboring Kenya, which they want to pressure into withdrawing its contingent from AMISOM.