Ethiopia has blamed Egypt for the failure of recent Khartoum-hosted talks between the water ministers of Sudan, Egypt and Ethiopia.
Last week, negotiations over Ethiopia's ambitious Grand Renaissance Dam project resumed in Sudan following a two-year hiatus.
"Egypt wanted Ethiopia to recognize a 1959 water-sharing treaty between Sudan and Egypt," Ethiopian Foreign Ministry spokesman Meles Alem told reporters on Thursday.
"But this is a red line for Ethiopia, which cannot be compelled to recognize an agreement signed in its absence," he said.
"There was a lack of goodwill on Egypt's part to move the consultations forward," Alem asserted, adding that the three water ministers nevertheless planned to meet again "soon".
According to the 1959 agreement, Egypt is entitled to 55.5 billion cubic meters of Nile water per year, while Sudan is entitled to 18 billion cubic meters.
Ethiopia, meanwhile, from which some 85 percent of the Nile River emanates, was not signatory to the agreement, which Addis Ababa, therefore, refuses to recognize.
It remains unclear whether Egypt will drop its insistence that Ethiopia recognise the 1959 agreement.
In 2011, Ethiopia began construction of a massive hydro-electric dam on the Blue Nile, a tributary of the Nile River, near the border with Sudan.
In the seven years since, Ethiopia, Egypt and Sudan have held several rounds of talks to discuss the dam's anticipated impact on Nile water resources.
Addis Ababa says electricity generated by the dam, which was originally slated for completion this year, will help eradicate poverty and contribute to the country's development.
Egypt, however, fears the dam could adversely affect its historical share of Nile water as defined in the 1959 water-sharing treaty.