Sudan warned Sunday it cannot continue the "vicious cycle" of negotiations with Egypt and Ethiopia in the long-running dispute over Addis Ababa's controversial Blue Nile mega dam.
Last week, the three countries had agreed to hold further talks to agree the filling and operation of the vast reservoir behind the 145-meter (475-foot) tall hydropower Grand Ethiopian Renaissance Dam (GERD).
But the latest meetings between foreign and water ministers "failed to reach an acceptable agreement to resume negotiations", Khartoum's state-run SUNA news agency said Sunday.
Sudan's water and irrigation minister, Yasser Abbas, warned that Khartoum cannot "continue this vicious cycle of indefinite talks".
Tensions have been high in the Nile basin ever since Ethiopia broke ground on the dam in 2011.
Ethiopia, the second most populous country in Africa, says the hydroelectric power produced by the dam will be vital to meet the power needs of its 110 million people.
Egypt, which depends on the Nile for about 97 percent of its irrigation and drinking water, sees the dam as an existential threat.
Khartoum hopes Ethiopia's dam will regulate annual flooding, but has also warned that millions of lives would be at "great risk" if no agreement was reached.
It says the water discharged from the GERD dam "poses a direct threat" to the safety of Sudan's Roseires Dam downstream on the Blue Nile.
The African Union, which is supporting the talks, suggested the three nations "hold bilateral meetings" with AU experts, Ethiopia's foreign ministry said in a statement Sunday.
While Ethiopia and Egypt accepted this proposal, "Sudan refused to have the bilateral meeting", the statement added.
Addis Ababa said it was "immediately" establishing a system to "cater for the concerns of Sudan on dam safety, data exchange and other technical issues", the ministry said.
Relations between Addis Ababa and Khartoum have deteriorated in recent weeks, with clashes reported along their frontier on the sidelines of an Ethiopian military operation in the Tigray region, bordering Sudan.
Ethiopia, which has said it reached its first-year target for filling the dam's reservoir, has recently signalled it would proceed with the filling regardless of whether a deal was concluded.
The Nile, the world's longest river, is a lifeline supplying both water and electricity to the 10 countries it traverses.
Its main tributaries, the White and Blue Nile, converge in the Sudanese capital Khartoum before flowing north through Egypt to drain into the Mediterranean Sea.