Cairo and Addis Ababa had previously been locked in a bitter war of words over Ethiopia’s $4bn project.

But in March, the leaders of the three countries signed a co-operation deal in Khartoum that paved the way for a joint approach to regional water supplies.

Compensation for damages

Following a two-day meeting of Egypt, Ethiopia and Sudan’s foreign and water ministers, Khartoum’s chief diplomat, Ibrahim Ghandour, said two French firms BRL and Artelia had been tapped for the work.

Technical studies will start in February, when the six ministers are due to meet again and will take between six and 15 months, said Sudanese Water Resources, Irrigation, and Electricity Minister Moataz Mousa.

The principles in the March agreement included giving priority to downstream countries for electricity generated by the dam, a mechanism for resolving conflicts and providing compensation for damages.

Signatories also pledged to protect the interests of downstream countries when the dam’s reservoir is filled.

Addis Ababa has long complained that Cairo was pressuring donor countries and international lenders to withhold funding from the 6 000 megawatt dam, which is being built by Italy’s largest construction firm Salini Impregilo SpA.

Egypt, which relies almost exclusively on the Nile for farming, industry and domestic water use, has sought assurances the dam will not significantly cut its flow to its rapidly growing population.

Power exporter

Even before the impact studies have been started, officials say 50% of the dam’s construction has been completed.

Ethiopia, the source of the Blue Nile which joins the White Nile in Khartoum and runs to Egypt, says the dam will not disrupt flow. It hopes the project will transform it into a power hub for the electricity-hungry region.

The Grand Renaissance Dam is the centrepiece of Ethiopia’s bid to become Africa’s biggest power exporter. Addis Ababa plans to spend about $12bn on harnessing its rivers for hydro power production in the next two decades.