Sudan's foreign minister has written to the UN Security Council to intervene on the row over Ethiopia's Grand Renaissance Dam on the Nile River.
Sudan wants the council to meet and discuss the dam's impact on the safety and security of millions of people.
Minister Mariam al-Mahdi's letter to the council head asks him to urge Ethiopia to stop the unilateral filling of the dam.
Ethiopia says the dam is vital for its development as it could bring power to 60% of the population. Sudan says filling the dam without solving outstanding issues would threaten national security.
Sudan wants Ethiopia to commit to a legally binding agreement, rather than guidelines, on the amount of water retained and the timetable for filling the reservoir.