Turkey needs to stop or significantly reduce the number of illegal migrants crossing into Europe and a readmission agreement between Ankara and Brussels must go into full effect by June 1, an EU envoy said on Friday. "A very important date will be the first of June, when all provisions of the Turkey-EU readmission agreement will have to apply and be fulfilled," Hansjorg Haber, head of the EU delegation to Turkey, told a news conference in Istanbul. "In the meantime, it is important to improve the application of the existing bilateral readmission agreement with Greece and Bulgaria.