Egypt says unilateral move violates international laws as tensions rise over huge dam built on Nile’s main tributary.

Egypt has said it received an official notice from Ethiopia that it had started the next phase of filling a controversial huge dam on the Nile River’s main tributary, raising tensions days before an upcoming meeting of the United Nations Security Council on the issue.

In a statement late on Monday, the Egyptian irrigation ministry expressed its “firm rejection of this unilateral measure” and said the move was “a violation of international laws and norms that regulate projects built on the shared basins of international rivers”.

The Grand Ethiopian Renaissance Dam (GERD), which is set to be Africa’s largest hydroelectric project when completed, is the source of an almost decade-long diplomatic standoff between Ethiopia and downstream nations Egypt and Sudan.

Addis Ababa says the project is essential to development, but the governments in Cairo and Khartoum fear it could restrict their citizens’ water access.

There was no immediate comment by Ethiopian government officials confirming that second-phase filling had begun.But a senior water ministry official told AFP news agency it would be in line with the calendar Ethiopia has long said it would follow.

Ethiopia argues that adding water to the reservoir, especially during the heavy rainfalls of July and August, is a natural part of construction. “Filling goes in tandem with the construction,” said a senior official at the water ministry. “If the rainfall is as you see it now in July, it must have begun.”

The volume of the accumulating water would depend on the amount of seasonal rain that fell in Ethiopia, Egyptian Irrigation Ministry spokesman Mohamed Ghanim told a local TV channel.

“We won’t see any effect now on the Nile. We have a month or a month and a half ahead of us,” he said.

Both Egypt and Sudan have been pushing Ethiopia to sign a binding deal over the filling and operation of the dam, and have been urging the UN Security Council to take the matter up in recent weeks.

Thursday’s meeting was requested by Tunisia on Egypt and Sudan’s behalf, a diplomatic source told AFP news agency. But France’s ambassador to the UN said last week that the council itself can do little apart from bringing the sides together.

Egypt’s Foreign Minister Sameh Shoukry said in a note to the UN that negotiations are at an impasse, and accused Ethiopia of adopting “a policy of intransigence that undermined our collective endeavours to reach an agreement”.

The Ethiopian government had previously announced it would proceed to the second stage of filling in July, with or without a deal.

The Nile – which at some 6,000km (3,700 miles) is one of the longest rivers in the world – is an essential source of water and electricity for dozens of countries in East Africa.

Egypt, which depends on the Nile for nearly all of its irrigation and drinking water, sees the dam as an existential threat.

Egyptian President Abdel Fattah el-Sisi warned Ethiopia earlier this year that his government would not tolerate any moves that would reduce Egypt’s share of water from the Nile.

He said that “all options are open” should Egypt’s share be “touched”, urging Addis Ababa to cooperate with Cairo and Khartoum to avert any conflict.

Sudan hopes the project will regulate annual flooding but fears its dams would be harmed without agreement on the Ethiopian operation.

The 145-metre (475-foot) mega-dam, on which construction began in 2011, has a capacity of 74 billion cubic metres.

Filling began last year, with Ethiopia announcing in July 2020 it had hit its target of 4.9 billion cubic metres – enough to test the dam’s first two turbines, an important milestone on the way towards actually producing energy.

The goal is to impound an additional 13.5 billion cubic metres this year.

Egypt and Sudan wanted a trilateral agreement on the dam’s operations to be reached before any filling began.

But Ethiopia says it is a natural part of the construction and is thus impossible to postpone.

Last year, Sudan said the process caused water shortages, including in Khartoum, a claim Ethiopia disputed.

Yasser Abbas, Sudan’s water minister, warned in April that if Ethiopia went ahead with the second stage of filling, his country “would file lawsuits against the Italian company constructing the dam and the Ethiopian government”.

He said the lawsuits would highlight that the “environmental and social impact as well as the dangers of the dam” have not been taken into adequate consideration.