The UN chief called Sunday on the M23 rebels in the Democratic Republic of Congo to lay down their weapons and leave the city of Goma which they have seized.Ban Ki-Moon said he welcomed a joint statement by the presidents of the former Zaire, Rwanda and Uganda making the same appeal at a summit Saturday in the Ugandan capital, Kampala."The secretary-general calls on the M23 to immediately lay down their arms in accordance with the agreements reached in Kampala, and comply with the immediate withdrawal of their forces from Goma," said a statement from Ban."The secretary-general encourages the parties to build on the dialogue among the leaders of the Great Lakes region to address the fundamental causes of conflict," it added.The M-23 rebels had said Saturday they would hold direct talks with DR Congo leader Joseph Kabila. But these never took place, and now there are rival demands over whether the rebels should quit Goma before or after talks are held.Agencies