The leaders of Sudan, Ethiopia and Egypt agreed that Ethiopia will delay filling a mega-dam on the Blue Nile and return to talks aimed at reaching an accord on use of the river's waters, according to statements from Cairo and Khartoum.

The announcement late on Friday was a modest reprieve from weeks of bellicose rhetoric and escalating tensions over the $4.6bn Grand Ethiopian Renaissance Dam, which Ethiopia had vowed to start filling at the start of the rainy season in July.

There was no immediate comment from Ethiopia on the agreement, beyond a tweet from Prime Minister Abiy Ahmed that described an African Union (AU) summit discussion about the dam as "fruitful".

Ethiopia won't fill the dam before inking the much-anticipated deal, Hamdok said in a statement, adding: "Sudan is one of the biggest beneficiaries from the dam and also one of the biggest losers if risks are not mitigated, thus it urges Egypt and Ethiopia to the impending necessity ... of finding a solution."

Sticking points in the talks have been how much water Ethiopia will release downstream from the dam if a multi-year drought occurs and how Ethiopia, Egypt and Sudan will resolve any future disagreements.