LISBON, Portugal -- A plane chartered by Angola's UNITA rebel movement slammed to the ground in a remote part of southern Angola, killing at least 136 people, UNITA said Wednesday.


Six people survived the crash, including one of the five crew members of the American-made Electra aircraft owned by Trans Service Airlift, a private air charter company based in Zaire, the group said.


UNITA said in a statement issued in Lisbon that the plane crashed two minutes after takeoff Monday five kilometers from the airport in Jamba, the rebels' former headquarters 900 kilometers southwest of the Angolan capital, Luanda.


It was the world's worst air disaster of the year. Before Monday's crash, the worst air disaster of 1995 involved a Russian Aeroflot Tu-154 which disappeared on Dec. 7 with 97 people on board and was found Monday.


The rebel statement did not say where the plane was headed when it crashed nor where the survivors were being treated. It was the first formal statement on the mysterious crash, and details remained unclear and impossible to independently verify.


Earlier reports from Zairian transport officials and state-run television and radio had said the crash took place in northern Angola and that the plane was carrying diamond miners from the Zairian capital of Kinshasa. Those reports said there were 139 dead and five survivors.


The purpose of the flight also was unclear. UNITA said the passengers were Angolan civilians being moved out of Jamba as part of UNITA efforts to relocate families that took refuge in the rebel stronghold during Angola's 20-year civil war.


UNITA claimed it had asked for international help in relocating the families to areas of their choice in Angola.


"The United Nations has refused up to now to evacuate these Angolan citizens,'' the rebel statement said. "So UNITA took up the responsibility of evacuating families whenever its resources permitted.''


UNITA -- the National Union for the Total Independence of Angola -- said investigators were combing the fuselage to determine the cause of the accident.


UNITA and the Angolan government are bound to a shaky peace treaty to end two decades of fighting, which has killed more than 500,000 Angolans and devastated a once-thriving economy. (AP, Reuters)