Ethiopia on Wednesday rejected a proposal by Egypt to operate a $4 billion hydropower dam the Horn of Africa country is constructing on the Nile, further deepening a dispute between the two nations over the project.

In a press conference in Ethiopia's capital Addis Ababa, Sileshi Bekele, minister for water, irrigation and energy described Egypt’s plan including the volume of water it wants the dam to release annually as “inappropriate.”

"The proposal from Egypt was unilaterally decided…(it) didn’t consider our previous agreements.” he said.

"We can't agree with this…we will prepare our counter-proposal.”

The Grand Ethiopian Renaissance Dam (GERD), announced in 2011, is designed to be the centre-piece of Ethiopia’s bid to become Africa’s biggest power exporter, generating more than 6,000 megawatts.

The two nations disagree over the annual flow of water that should be guaranteed to Egypt and how to manage flows during droughts.

Egypt relies on the Nile for 90% of its fresh water and it wants the GERD's reservoir to release a higher volume of water than Ethiopia is willing to guarantee, among other disagreements.

"An Egyptian expert can't control our dam.” Sileshi said and described the Egyptian plan as a potential violation of Ethiopia’s sovereignty.

Sileshi did not say how much water Ethiopia wants to release, but Egypt wants the dam to release a minimum of 40 billion cubic metres of water from the GERD annually.

Following construction delays, Ethiopia has said GERD will start power production by the end of 2020 and be fully operational by 2022.