Khartoum, March 23 : Sudan has urged Ethiopia to accept a mediation quartet regarding the issue of the disputed Grand Ethiopian Renaissance Dam (GERD) on the Nile river. "Ethiopia should accept the mediation quartet of the US, the European Union, the US and the African Union to reach a fair and legal agreement," Sudanese Irrigation and Water Resources Minister Yasir Abbas said here on Monday. Ethiopia had earlier announced its decision to reject the mediation quartet. In February, the country said it would carry on with the second-phase 13.5-billion-cubic-meter filling of the GERD in June. The volume of the first-phase filling last year was 4.9 billion cubic meters. Sudan, Egypt and Ethiopia have been in talks for years over the technical and legal issues related to the filling and operation of the GERD. Ethiopia, an upstream Nile basin country, started building the GERD in 2011, while Egypt is concerned that the dam might affect its 55.5-billion-cubic-meter annual share of the Nile water. Sudan has recently been raising similar concerns over the $4 billion dam. Over the past few years, tripartite talks on the rules of filling and operating the GERD, with a total capacity of 74 billion cubic meters, have been fruitless. Ethiopia carried out the first phase of filling the dam in July 2020 and is expected to start the second phase later this year. /IANS