Sudan boycotted talks on Saturday between Nile Valley countries over Ethiopia's controversial mega-dam, calling on the African Union to play a greater role in pushing forward the negotiations that have stalled for years, dpa reported. It was the first time that Sudan refused to attend talks with Ethiopia and its northern neighbor Egypt, which has expressed for years its fears that the Ethiopian Grand Renaissance dam on the Blue Nile will dramatically threaten water supplies downstream. Sudanese Irrigation Minister Yasser Abbas said in a statement that the current approach to reaching a tripartite agreement on the filling and operation of Ethiopia's dam had not yielded results, and the AU should do more to facilitate the negotiation and bridge the gap between the three parties. Sudan's boycott, however, could derail the complicated talks, which the AU has already taken the lead role in supporting. On Thursday, the foreign and irrigation ministers of the three Nile Valley countries met online, two weeks after they failed to agree on a new framework for negotiations. There were no immediate comments from South Africa, which heads the African Union, Egypt or Ethiopia to Saturday's move by Sudan. It was not clear when they would restart negotiations.