Angolan rebels claimed they drove off Marxist government forces in a 10-hour battle on the northern banks of the Lomba river in Angola's southern Cuando Cubango province. In a statement issued in Lisbon, the rebel National Union for the Total Independence of Angola said its forces killed 232 government troops and seven Soviet nationals and that 20 of its fighters died. It also reported the capture of four Soviet-made tanks. There was no immediate comment from Luanda, the Angolan capital. Angolan troops, backed by Cuban support units and Soviet military advisers, have been engaged in an offensive in Cuando Cubango province in recent weeks.