Sudan asked the UN Security Council on Tuesday to meet and discuss a dispute over a giant dam being built by Ethiopia on the Blue Nile, the government said.
Ethiopia is pinning its hopes of economic development and power generation on the Grand Ethiopian Renaissance Dam.
But downstream countries Egypt and Sudan are seeking a binding agreement on its filling and operation.
Egypt relies on the Nile River for as much as 90 per cent of its fresh water and regards 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 Al Mahdi, called on the Security Council to hold a session as soon as possible to discuss the dam and "its impact on the safety and security of millions of people", the government said.
Ms Al Mahdi wrote to the council asking it to urge Ethiopia to stop the reservoir filling, "which exacerbates the dispute and poses a threat to regional and international peace and security", it said.
Ethiopian officials did not immediately provide comment.
Sudan and Egypt 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.
This month, Arab states called on the Security Council to discuss the dispute and Ethiopia's plans for its filling.
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.