U.N. Secretary-General Ban Ki-moon on Friday spoke by telephone with the leaders of Egypt and Ethiopia over the latter's proposed Nile dam project, his spokesman said Friday. Two weeks ago, Ethiopia announced that it had begun to divert the Blue Nile, the major source of Egypt's water, in the process of building a giant dam. Egypt has said any water diversion is potentially catastrophic. "The secretary-general spoke by telephone on Thursday with Egyptian President Mohammed Morsi and today with Ethiopian Prime Minister Hailemariam Desalegn," Ban spokesman Martin Nesirky said in an e-mail to reporters. "He spoke with both leaders about the proposed dam project on the Nile River and expressed his desire that they engage in dialogue to resolve differences on that matter," the e-mail added.