Sudan has denied an Ethiopian proposal to manage the filling for a second time of a giant dam that it is building on the Blue Nile, a senior official said on Sunday, deepening a regional conflict over the project.

Ethiopia has pinned hopes of development and power generation on the Grand Ethiopian Renaissance Dam (GERD), while downstream Sudan is concerned about regulating flows to its own dams and Egypt fears an impact on its water supply.

Addis Ababa has said it will again fill the reservoir behind the multi-billion dollar hydropower dam after seasonal rains start this summer, a move that both Sudan and Egypt oppose without a binding deal on filling and operating the dam.