A view of the Nile River and the Cairo city is seen from the Cairo Tower in Cairo, Egypt, Nov. 24, 2019. (Xinhua/Wu Huiwo)

Egypt, Ethiopia and Sudan have failed to reach an agreement at a new round of talks hosted by the African Union to regulate the flow of water from the giant Blue Nile hydropower dam built by Addis Ababa, the three countries said.

The African Union launched its mediation effort two weeks ago, involving 11 online sessions to end the deadlock over the filling and operation of the $4 billion Grand Ethiopian Renaissance Dam (GERD) on the Blue Nile, which flows into the Nile river.

The dam is the centerpiece in Ethiopia's bid to become Africa's biggest power exporter, but has sparked concerns in Cairo that Egypt's already scarce supplies of Nile waters, on which its population of over 100 million people is almost entirely dependent, would be further restricted.

"Unchanged and additional and excessive demands of Egypt and Sudan prohibited the conclusion of this round of negotiation by an agreement," the Ethiopian foreign ministry said on Tuesday.

It did not elaborate but said Ethiopia was willing to show flexibility as talks would continue.

The Egyptian irrigation ministry said on Monday that all three countries would submit a report on the talks to mediator Cyril Ramaphosa, the South African President and the African Union's President who is preparing a new mini summit.

"The desired goal is to always reach an agreement and it is the thing we are trying to achieve," Egyptian Foreign Minister Sameh Shoukry told local TV.

Sudan's Information Minister, Faisal Saleh, said on Monday that the issue must be resolved through dialogue, and a fair solution was necessary to limit the negative impact of the dam.

The three countries had been expected to sign an agreement in Washington in February but Ethiopia skipped the meeting and only Egypt initialed the deal.

The GERD is being built about 15 kilometers from the border with Sudan on the Blue Nile, source of most of the Nile's waters.

Sudan and Egypt have sought a legally binding agreement before the dam is filled, which Ethiopia said would start in July using seasonal rains.

Reuters