Tensions mount as Ethiopia allows dam across Nile headwaters to fill

Egypt fears hydroelectric project will restrict limited waters on which its population depends

Ethiopia has allowed a controversial dam built across the headwaters of the Nile to fill with rain water, raising tensions with Egypt and Sudan.

The huge hydroelectric project on the Blue Nile, known as the Grand Renaissance dam, is at the centre of Ethiopia's plan to become Africa's biggest power exporter, but Egypt fears already limited Nile waters, on which its population of more than 100 million people depends, might be restricted.