A total of 514 migrants arrived on the Greek Aegean islands from Turkey in the 24 hours to Sunday morning, officials said, the day before a deal to return such migrants to Turkey goes into effect, dpa reported. On Saturday, the figure was 566 migrants, on Friday 339 and on Thursday 377, the Greek department dealing with the refugee crisis said. The department said that as of Saturday there were more than 52,500 refugees and other migrants stranded in Greece after countries further along the so-called Balkan route to northern and western Europe closed their borders to people without valid documents. On Monday, the deal between the European Union and Turkey to send back to Turkey from the Greek islands of Lesbos and Chios any migrants unlikely to gain asylum comes into effect.