Ethiopia has officially inaugurated Africa's largest hydroelectric dam, a project that will provide energy to millions of Ethiopians while deepening a rift with downstream Egypt that has unsettled the region.

Ethiopia, the continent's second most populous nation with more than 120 million people, sees the $US5 billion ($A7.6 billion) Grand Ethiopian Renaissance Dam on a tributary of the River Nile as central to its economic ambitions.

The dam's power has gradually increased since the first turbine was turned on in 2022, reaching its maximum capacity of 5150 megawatts on Tuesday.

That puts it among the 20 biggest hydroelectric dams in the world - about one-quarter of the capacity of China's Three Gorges Dam.

At a ceremony on Tuesday at the site in Guba, an Ethiopian fighter jet flew low

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