Egypt, Sudan and Ethiopia have failed again to make progress on their Nile dispute as Ethiopia works to complete a massive upstream dam, an Egyptian official said Tuesday.

Egypt fears the Renaissance Dam will cut into its share of the river, which provides virtually all the freshwater for the arid country of 100 million people. Ethiopia, which has the same sized population, says the dam is essential for its economic development.

Technical talks among irrigation ministers of the three countries in the Ethiopian capital, Addis Ababa, last week ended with no deal, Hossam el-Emam, a spokesman for Egypt's Irrigation Ministry, told The Associated Press.

Ethiopia and Sudan still insist on modifications to a technical report by a French firm commissioned to assess the dam's impact, he said.

"Such modifications get it out of its context," he said, adding that there may be another round of talks May 15. "We hope to make a breakthrough in the coming meeting ... Time is not in our favor," he said.

Last month, Egypt's Foreign Minister Sameh Shoukry warned that Egypt "will not accept the status quo" and "continues to defend the interests of its people regarding the Nile by several means," without elaborating.

The $4.8 billion dam is now 63 percent finished, and Ethiopia hopes to become a key energy hub in Africa upon its completion.

The main sticking point with Egypt concerns how quickly the reservoir behind the dam is filled, and the impact that will have downstream.

Egypt has received the lion's share of the Nile's waters under decades-old agreements seen by other Nile basin nations as unfair. Past Egyptian presidents have warned that any attempt to build dams along the Nile will be met with military action, but Egypt's current leader, President Abdel-Fattah el-Sissi, has ruled that out.

Sudan appears to be taking Ethiopia's side in the negotiations, and has revived a longstanding border dispute with Egypt.