An official statement by the Egyptian Ministry of Foreign Affairs said that the step was announced "unilaterally" as was the case in the first and the second filling of the multi-billion-dollar dam in 2020 and 2021.

Earlier in the day, Ethiopian Prime Minister Abiy Ahmed congratulated Ethiopians as the GERD's first turbine began generating power during a ceremony.

The DoP, signed in March 2015 by the three countries in Khartoum to settle the GERD crisis, granted Ethiopia the consent of the two downstream countries of Egypt and Sudan to the construction of the dam in return for a pledge from Ethiopia not to inflict any harm on the downstream countries.

The 10-principle DoP obliges the three countries to take all the necessary procedures to avoid causing significant damage among them while using the Blue Nile.

A state whose use of the Blue Nile causes significant harm to any of the other two countries, in the absence of an agreement, should take all appropriate measures in consultations with the affected state to eliminate or mitigate such harm, according to the DoP.

Egypt and Sudan, who do not oppose the construction of the dam, have been negotiating with Ethiopia for 10 years now to reach a legally binding agreement on the rules of filling and operating the GERD, but Addis Ababa has repeatedly refused to sign any such deal.

Egypt, which relies mainly on the Nile for its water needs, fears that the unilateral and quick filling and operation of the GERD would have a negative impact on the country's water supply. Meanwhile, Sudan is concerned about regulating water flows to safeguard its own dams.

The latest rounds of African Union (AU)-sponsored talks in Kinshasa to resolve the decade-long dispute collapsed in April, with Egypt and Sudan having always blamed the failure of this and previous rounds of talks on Ethiopia's intransigence.

Ethiopia, which says the project essential for producing electricity and economic development, has repeatedly downplayed the concerns of Cairo and Khartoum.

Addis Ababa unilaterally completed the dam's first filling in 2020 and the second filling in 2021 in the absence of a legally binding deal with Cairo and Khartoum.

During Sunday's event, Abiy Ahmed said "From now on, there will be nothing that will stop Ethiopia," according to AP.

The now-operating first turbine generates 375 megawatts, while the second turbine is also in preparation, the Ethiopian News Agency reported, adding that when the construction of the dam is complete, it will generate 5,250 megawatt of electricity.

The GERD’s project manager Kifle Horo said, according to AP, that the dam “just started generating power, but that doesn't mean the project is completed”.

“It will take from two and half to three years to complete it [the GERD],” Horo said.