Egypt's president says he expressed his "extreme concern" over the lack of progress in talks over the construction of a massive Nile dam in Ethiopia during a meeting with that country's visiting prime minister.

Egypt fears the dam, which is about 60 percent complete, will significantly reduce its vital share of the Nile's waters. Ethiopia has downplayed those fears and said it needs the dam for its own economic development.

A grim-faced President Abdel-Fattah el-Sissi emerged from a meeting in Cairo on Thursday with Ethiopian Prime Minister Hailemariam Desalegn, saying cooperation between Nile basin countries should not be a zero-sum game. El-Sissi says Ethiopia has rejected an Egyptian proposal for World Bank experts to mediate the dispute.

Egypt depends on the Nile for almost all of its water needs.