Spanish Prime Minister Jose Luis Rodriguez Zapatero today warned Israeli Foreign Minister Avigdor Lieberman of the risk of stagnation in attempts to revive the Middle East peace process, dpa cited government sources as saying. Lieberman was received in Madrid by Zapatero, whose country holds the rotating European Union presidency. "The biggest risk for the (Middle East) region is that there are no advances in the peace process," the sources quoted Zapatero as saying. Zapatero told Lieberman that Israel should reopen the dialogue with the Palestinians. The two also discussed the June summit of the Union for the Mediterranean in Barcelona, which Spain regards as being important for the peace process. Lieberman was also scheduled to meet his Spanish counterpart, Miguel Angel Moratinos, during his visit.