CAIRO -- Egyptian President Abdel Fattah al-Sisi on Sunday said Egypt's water security is an "existential issue" and rejected any unilateral measures on the Nile River, the presidency said in a statement.

In a recorded speech for the opening of Cairo Water Week, Sisi said the Grand Ethiopian Renaissance Dam (GERD), built by Ethiopia upstream, must be governed by a legally binding agreement to ensure fair use of the river's water.

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"Egypt clearly and firmly rejects any unilateral measures on the Nile that ignore international norms, threaten the peoples of the basin, and undermine justice and stability," Sisi said.

He added that development "is not the privilege of a single country but a shared responsibility among all peoples of the river," calling for cooperation rather than unilateral action.

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Egypt and Sudan, both downstream countries, have repeatedly voiced concern over their water shares since Ethiopia began building the GERD. Years of talks among the three nations have yet to yield a binding deal on filling and operating the dam.