Sudan asked the United Nations Security Council on Tuesday to meet and discuss a dispute over a giant dam being built by Ethiopia on the Blue Nile, a government statement said.

Ethiopia is pinning its hopes of economic development and power generation on the Grand Ethiopian Renaissance Dam (GERD), while the two downstream countries – Egypt and Sudan – are concerned about it and seeking a binding agreement on the filling and operation of the dam.

Egypt relies on the Nile River for as much as 90 perccent of its fresh water and sees the dam as an existential threat. Sudan is concerned about the operation of its own Nile dams and water stations.

Sudan’s Foreign Minister Mariam Sadiq al-Mahdi called on the Security Council to hold a session as soon as possible to discuss GERD and “its impact on the safety and security of millions of people,” the government statement said.

In a letter to the council head, she called on him to urge Ethiopia to stop the “unilateral” filling of the dam “which exacerbates the dispute and poses a threat to regional and international peace and security,” the statement added.

Ethiopian officials did not immediately return messages seeking comment.

Sudan and Egypt had already agreed this month to work together on all levels to push Ethiopia to negotiate “seriously” on an agreement, after African Union-sponsored talks remained deadlocked. The two countries called on the international community to intervene.

Earlier this month, Arab states called on the Security Council to discuss the dispute and Ethiopia’s plans to go ahead with the second filling of the dam this summer even without an agreement with Sudan and Egypt.

Ethiopia rejected the Arab League resolution in its entirety, its Foreign Ministry said.

The country previously rejected calls from Egypt and Sudan to involve mediators outside the African Union.

Sudan said earlier in June that it was open to a partial interim agreement on the multibillion-dollar dam, with specific conditions.