Sudan boycotted ministerial talks with Egypt and Ethiopia about a disputed dam being built on the Nile.
The move came in protest against what Khartoum said was the lack of response to its request for a meeting with African Union experts.
Sudan’s action was confirmed by the Egyptian government, which said the dialogue had to be abandoned as a result.
It came on the second day of talks between the three African nations over the operation of the Grand Ethiopian Renaissance Dam.
Sunday’s meeting, which ended a month-long break, brought together the foreign and water ministers from each country.
Officials agreed on Sunday that talks among the three water ministers and their teams of experts should continue for a week.
Foreign ministers would join them for a meeting on January 10 to review progress.
But Sudan’s boycott derailed that plan.
The talks, sponsored by the African Union, were held online because of the coronavirus pandemic.
Sudan said it did not get a response to its demand, but instead received an invitation to take part in Monday’s talks.
“This forced Sudan to stay away to emphasise its steadfast position that it is necessary to give the African Union experts a role to facilitate the negotiations and narrow the gap between the three parties,” Khartoum said.
Sudan was still committed to the negotiations, officials said.
The almost complete hydroelectric dam is regarded as an existential threat by Cairo.
Egypt and fellow downstream nation Sudan have been trying to persuade Ethiopia to enter a legally binding deal on the dam’s operation and ways to handle future disputes and persistent droughts.
The Sudanese boycott is the latest in a seemingly endless series of obstacles in nearly a decade of negotiations.
The Nile provides more than 90 per cent of Egypt’s water needs.
Cairo fears a significant drop in its share of the river’s water as a result of the dam would mean the loss of hundreds of thousands of jobs and the disruption of its sensitive food supply.
For Sudan, the absence of co-ordination on operating the dam built close to its border could spell disaster for its eastern food-producing region through flooding and the disabling of its hydroelectric Nile dams.
Recent tensions further diminish the chances of a breakthrough.
On Thursday, Cairo summoned the Ethiopian charge d’affaires to complain about comments made by Dina Mufti, the Ethiopian Foreign Ministry spokesman, accusing Egypt of using the dispute over the dam project to cover its internal problems.
Troops from Sudan and Ethiopia have had deadly clashes over a disputed border, which flared up recently just as Ethiopian federal forces were fighting separatist rebels in the restive Tigray region.
That conflict, which began in November, has forced tens of thousands of mainly Tigrayans to flee their homes and seek refuge in Sudan.