Dozens of Egyptian protesters gathered outside the Ethiopian embassy in Cairo on Friday to protest Addis Ababa's decision earlier this week to temporarily divert the course of the Blue Nile as part of a project to build a series of dams on the river.
Protesters held banners aloft reading, "We reject attempts to take our Nile Water." Others chanted: "We are the source of the Nile Basin."
"After Ethiopia's surprising decision, bilateral relations have now been put to the test," according to a statement by the 'Copts without Borders' group, one of the protests' main organisers.
The statement added: "Any agreement between President Mohamed Morsi's government and its Ethiopian counterpart will not be recognised, since Morsi has lost all legitimacy before the Egyptian people."
The statement went on to call on Egyptians to take part in a planned anti-Mors rally on 30 June to call for snap presidential elections.
Other participants at Friday's protest included members of the 'Lawyers Union for the Nile Basin' and the 'Egyptians against Injustice' movement.
Within the context of a plan to build a series of new dams for electricity production, Ethiopia on Tuesday began diverting the course of the Blue Nile, one of the Nile River’s two main tributaries. Most Nile water that reaches Egypt and Sudan originates from the Blue Nile.
Ethiopia's 'Renaissance Dam' project – one of four planned hydro-electric power projects – has been a source of concern for the Egyptian government, amid ongoing sensitivities regarding the project's possible effects on Egypt's traditional share of Nile water.
According to the state-run National Planning Institute, Egypt will need an additional 21 billion cubic metres of water per year by 2050 – on top of its current quota of 55 billion metres – to meet the needs of a projected population of some 150 million.