Egypt delivered on Monday the letter to the current President of the UNSC and Russian Permanent Representative to the UN Vassily Nebenzia, where it affirmed that the Ethiopian move constitutes "a material breach" of the Declaration of Principles (DoP) singed in 2015.

The same letter was sent a day earlier by Egypt’s irrigation minister to his Ethiopian and Sudanese counterparts.

"Egypt categorically rejects Ethiopia's unilateral commencement of operations of the GERD and holds Ethiopia accountable for its violation of its obligations under applicable rules of international law and of the DoP, and for any significant harm that befalls Egypt as a consequence of such violation," said the Egyptian letter, a copy of which has been seen by Ahram Online.

On Sunday, Ethiopian Prime Minister Abiy Ahmed announced the beginning of power generation from the first turbine of the GERD – a source of regional dispute since 2011– during an official ceremony in Guba.

In its letter, Egypt emphasised that the DoP "clearly and unequivocally" requires Ethiopia to reach a legally binding agreement governing the rules for the filling and operation of the GERD before commencing any of the two processes.

The 10-principle DoP was signed by President Abdel-Fattah El-Sisi, the now-ousted Sudanese president Omar Al-Bashir, and then-Ethiopian Prime Minister Hailemariam Desalegn in Khartoum in March 2015.

Egypt, which relies mainly on the Nile for its water needs, fears that the unilateral filling and operation of the GERD will have a negative impact on the country’s already scarce supplies. Meanwhile, Sudan is concerned about regulating water flows to safeguard its own dams.

However, Ethiopia, which says the project is essential for producing electricity and economic development, has repeatedly downplayed the concerns of Cairo and Khartoum during several rounds of negotiations following the signing of the DoP.

Egypt’s letter underscored that the Ethiopian practices, in reference to the unilateral filing and operation of the GERD, "will have a direct adverse impact on the riparian rights and interests of Egypt, and threaten to inflict significant harm on it."

Egypt and Sudan had condemned Addis Ababa’s unilateral first filling in 2020 and the second filling in 2021 in the absence of a legally binding deal.

Ahead of the first and second filling, Egypt and Sudan resorted twice to the 15-member UN body, urging in separate statements dissuading Ethiopia from taking any unilateral acts, but to no avail.

The unilateral operation of the GERD comes amid attempts to revive the talks between the three countries. The African Union (AU) sponsored Kinshasa talks, which stalled in April 2021, were the latest round of the decade-old negotiations on the now near-complete dam.

The letter further highlighted other outstanding points during the talks, saying Ethiopia failed to "undertake the requisite studies on the hydrological, socio-economic and environmental impacts of the GERD and to consult in advance with its co-riparian states, in compliance with Ethiopia's obligation under the established principles of customary international law."

The letter also cited the UNSC's presidential statement issued in September 2021, saying it called upon the parties to “take forward the negotiations, in a constructive and cooperative manner, to finalise expeditiously the text of a mutually acceptable and binding agreement on the filling and operation of the GERD within a reasonable timeframe."

"Eschewing unilateralism is not only a pillar of constructiveness and cooperation but also an indispensable requirement to comply with the Security Council's presidential statement," the letter added.

Sudan, meanwhile, voiced its rejection of Ethiopia’s unilateral acts in a statement issued on Monday, in which it said the step represented a “fundamental breach” of Ethiopia’s international legal commitments.