Ethiopian Prime Minister Abiy Ahmed inaugurated electricity production at the controversial, multi-billion-euro Grand Renaissance dam on the Blue Nile on Sunday. Downstream neighbours Egypt and Sudan view the project as a threat to their share of Nile waters.
The Grand Ethiopian Renaissance Dam (GERD) is set to be the largest hydroelectric scheme in Africa but has been at the centre of a regional dispute over water rights ever since work first began in 2011.
Addis Ababa deems the project essential for Ethiopia's electrification and development.
The 3.7-billion-euro project is ultimately expected to produce more than 5,000 megawatts of electricity, more than doubling Ethiopia's total output.
State media reported that the dam had started generating 375 megawatts of electricity from one of its turbines on Sunday.
The 145-metre high dam lies on Blue Nile River in the Benishangul-Gumuz region of western Ethiopia, not far from the border with Sudan.
Egypt, which depends on the Nile for about 97 percent of its irrigation and drinking water, sees the dam as an existential threat.
Sudan hopes the project will regulate annual flooding, but fears its own dams could be harmed without agreement on the GERD's operation.
Both countries have been pushing Ethiopia for a binding deal over the filling and operation of the massive dam, but talks under the auspices of the African Union (AU) have failed to reach a breakthrough.
The dam was initiated under former Prime Minister Meles Zenawi, the Tigrayan leader who ruled Ethiopia for more than two decades until his death in 2012.
Civil servants contributed one month's salary towards the project in the year of the project launch, and the government has since issued dam bonds targeting Ethiopians at home and abroad.
Officials on Sunday credited Abiy with reviving the dam after alleged mismanagement delayed its progress.