Egypt has submitted a complaint letter to the UN Security Council in protest to Ethiopia's plan to fill the controversial hydro-power dam project known as Grand Ethiopian Renaissance Dam (GERD).
Ethiopia is set to begin filling GERD reservoir in June and July raising serious concerns from Egypt.
The water filling strategy for the dam has long been the most contentious issue and yet unresolved in the Nile talks between Ethiopia, Egypt and Sudan.
According to local news agency, Ethiopian-Insider, Egypt's Minister of Foreign Affairs has submitted a 15-page complaint letter to the Security Council via Mohammed Endris, the Egyptian ambassador to the UN.
"Ethiopia's unilateral filling of GERD before reaching a final agreement with downstream countries on the rules governing the filling and dam operation is inconsistent with the spirit of cooperation between co-riparian countries that share an international watercourse and amounts to material breach of Ethiopia's legal obligations" Egypt said in the complaint letter seen by the The EastAfrican.
Cairo warned that Ethiopia's move potentially poses a serious threat to regional peace and security.
The desert north Africa's nation said that the unilateral filling of the dam could cause significant harm to its people who solely are dependent on the water resource of the Nile River.
"This [filling the dam] would jeopardise the water security, food security and indeed the very existence of over 100 million Egyptians who are entirely dependent on the resource of the Nile River for their livelihoods"
"The prospect of being subjected to significant harm to its riparian rights and interests would be wholly intolerable for Egypt" the Egyptian complaint document added.
The document also warns that water filling strategy should not be initiated through Ethiopia without consulting downstream countries.
Egypt further said that Ethiopia's move in 2011 to launch the massive dam project without notifying or consulting downstream countries was in violation to its obligation under international law.
However, Cairo didn't state how it was an infringement to international law.
Egypt said that it has been in serious negotiations with Ethiopia after the latter commenced construction of the multi-billion dollar power plant project being built along the Nile River near the Sudanese border.
In these negotiations, Egypt has told the Security Council that "it has exercised considerable flexibility, showed limitless goodwill and demonstrated genuine political commitment" in a bid to reach a fair and balanced agreement to the long-standing row on utilisation of the Nile water resources.
Tensions between Ethiopia and Egypt strained after Ethiopia skipped the last round of talks held in Washington on February 26, saying it needed more time for consultations at home.
However, Cairo who brought on board the US and the World Bank to the negotiation table, signed a draft document, indicating negotiations had been completed.
After Washington talks failed, Addis Ababa and Cairo have traded accusations over the failure of the US-led negotiations.
Cairo then accused Ethiopia of "deliberately" hindering the path of negotiations and vowed to use all available means to defend the interests of its people.
Ethiopia on its side held Egypt accountable for the failure of the negotiations.
"Egypt bears the full responsibility of hampering negotiations and involving external parties in the negotiations" said Gedu Andargachew, Ethiopia's foreign affairs minister, late in March.
Ethiopia pulled out of the talks over what it said was in protest to the US and the World Bank overstepping their roles and favouring Cairo's interest.
Previously, Ethiopian negotiating officials have complained that the role of America had "gone beyond observer's role" and further accused the US of putting pressure on Ethiopia to sign the agreement.
On part of the attached document to the Security Council, Egypt argues that "this agreement is beneficial for all parties, contains a fair formula and is equally important to the interests of the three countries" and asked Ethiopia to sign the agreement.
Ethiopian officials were not immediately available for comments on Egypt's latest complaint it submitted to the UN executive body.
However, speaking to Ethiopia-Insider, Ethiopia's Ministry of Foreign Affairs' acting spokesperson, Mr Amsalu Tiezzazu, downplayed Cairo's complaints saying "This an unfounded allegation"
"We know that the complaint has been filed" said Amsalu indicating Egyptian latest course was an unwise one.
"Ethiopia will submit the necessary response to the UN Security Council," he added.
While noting that the GERD is a project of the people of Ethiopia, the official however stressed that Egypt's complaint will not delay Ethiopia's plans to fill the dam.
Ethiopia says the issue of the Nile dam is a matter of the three countries, and should be resolved between the three countries.
Addis Ababa insists that the huge dam project will not significantly affect Egypt and Sudan, but instead will benefit them with supply of cheap and renewable hydro power.
The dam, poised to be Africa's largest upon completion, will have capacity of generating 6,000 megawatts of electricity.
The EastAfrican has learnt that, currently, 73 per cent of the Hydro-dam project is completed and is expected to start generating electricity with initial two turbines after Ethiopia fills the dam reservoir in the coming rainy season.