Egyptian President Abdel Fattah al-Sisi and Ethiopian Prime Minister Abiy Ahmed met on the sidelines of Russias Africa summit on Thursday to discuss a disputed Nile dam, a diplomatic source told Agence France Presse. Sisi "delivered a message" to Abiy about Addis Ababas soon-to-be-finished dam on the Blue Nile, the Egyptian diplomatic source said. The meeting lasted around 45 minutes and took place "in a positive atmosphere," the source added, without providing details. Egypt fears that the building of the Grand Ethiopian Renaissance Dam (GERD), a $4 billion project begun in 2012, will reduce the flow of the Nile. Discussions between the two countries and with Sudan, through which the river also passes, have been blocked for nine years. Russia, which is hosting a two-day Africa Summit in its Black Sea resort of Sochi, has said it is ready to play a role in resolving the conflict. "The dam... was discussed during (Russian President Vladimir Putins) meeting with the President of Egypt, and during a meeting with the Prime Minister of Ethiopia," Kremlin spokesman Dmitry Peskov. Putin told the two leaders they should take advantage of their presence in Sochi to "directly discuss (their) concerns" and that he also offered "his assistance", Peskov said. In early October, negotiations in Khartoum resulted in a "stalemate", according to Cairo, which has since sought international mediation. Ethiopia has rejected the claim, calling it "an unwarranted denial of the progress" made during the negotiations. Egypt, which depends for 90 percent of Niles water supply, said on Tuesday it had accepted a US invitation to a meeting of foreign ministers over the giant hydropower dam. The meeting of foreign ministers of Egypt, Ethiopia and Sudan will be held in Washington, Egypts foreign ministry said. Ethiopia says GERD is crucial to its economic development.