Rebels said Friday they had overrun three more government garrisons in southern Sudan and beaten back a military convoy trying to stage a rescue mission. In a clandestine radio broadcast, the Sudan People's Liberation Army said it captured Kologi in southern Kordofan province on Wednesday ``after seven days of heavy fighting preceded by a one-month siege.'' The broadcast said rebel forces also ambushed a 33-vehicle convoy, including four tanks, that was trying to reach Kologi and ``forced it to retreat with heavy losses.'' The rebels also claimed the capture of two smaller garrison towns, Bazia on Jan. 24 and Amati on Wednesday. The report could not be independently confirmed, but if true would bring to more than 15 the number of garrisons captured by the rebels the past three months.