The latest round of African Union-led talks to resolve the years-long dispute over a controversial dam that Ethiopia is building on the Blue Nile River has met with another stalemate.

Foreign and irrigation ministers of Egypt, Sudan and Ethiopia met in Kinshasa, the capital of the Democratic Republic of Congo, the current chair of the African Union.

The talks sought to find an agreed-on approach to resume negotiations on the filling and operation of the Grand Ethiopia Renaissance Dam but the four days of meetings concluded without a breakthrough.

Ethiopia rejected a Sudanese proposal, backed by Egypt, to include international mediators in the talks, while Egypt’s top diplomat said they would again take the dispute to the U.N. Security Council.

Spokesperson of Egypt’s Foreign Ministry, Ahmed Hafez, said Addis Ababa rejected expanding the mediation umbrella to include the United States, the European Union, and the United Nations along with the AU.

Sudan’s Irrigation Ministry also criticized Ethiopia, saying its announced plan to add 13.5 billion cubic meters of water to the dam’s reservoir this year is a real threat which cannot be accepted.

In a brief statement posted on Facebook, Ethiopia’s foreign minister Demeke Mekonnen said his country appreciated AU efforts to resume the process to reach a win-win outcome and invited Egypt and Sudan to follow suit.

Sudan wants Ethiopia to coordinate and share data on the dam’s operation to avoid flooding and protect its own power-generating dams on the Blue Nile, the main tributary of the Nile River.