ADDIS ABABA (Reuters) – Ethiopia began diverting a stretch of the Nile on Tuesday to make way for a $4.7 billion hydroelectric dam that is worrying downstream countries dependent on the world’s longest river for water.

The Horn of Africa country has laid out plans to invest more than $12 billion in harnessing the rivers that run through its rugged highlands, to become Africa’s leading power exporter.

Centerpiece to the plan is the Grand Renaissance Dam being built in the Benishangul-Gumuz region bordering Sudan. Now 21 percent complete, it will eventually have a 6,000 megawatt capacity, the government says, equivalent to six nuclear power plants.

“The dam is being built in the middle of the river so you can’t carry out construction work while the river flowed,” said Mihret Debebe, chief executive officer of the state-run Ethiopian Electric Power Corporation, at a ceremony at the site.

“This now enables us to carry out civil engineering work without difficulties. The aim is to divert the river by a few meters and then allow it to flow on its natural course.”

Ethiopia’s ambitions have heightened concerns in Egypt over fears the projects may reduce the river’s flow. Addis Ababa has long complained that Cairo was pressuring donor countries and international lenders to withhold funding.

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