A Turkish official says Greece has postponed the next transfer of migrants to Turkey until Friday.

The delay, if confirmed, comes one day after the first group of more than 200 migrants were shipped back to Turkey on Monday, under a deal agreed with European Union leaders. The Greek government earlier said the deportation process had been slowed by an increase in asylum requests by migrants on the islands of Chios and Lesbos.

Under the pact with the EU, Turkey has agreed to take back migrants who arrived in Greece by crossing the Aegean Sea illegally after March 20.