Turkish President Recep Tayyip Erdoğan has instructed the coastguard to no longer allow migrants to attempt to cross the Aegean Sea to go to the European Union, citing their safety.
"Illegal migrant crossings via the Aegean Sea are not allowed for it is dangerous," said a statement from the coastguard, citing a presidential order.
The Interior Ministry will oversee the implementation of the order.
"While the principal of not intervening with the illegal migrants wanting to leave Turkey remains to be implemented, such an approach does not cover sea crossings due to life-threatening danger," it added.
The coastguard accused Athens of volating international law by putting migrant boats at risk, saying it rescued nearly 100 migrants from three boats on Thursday that had been left half-sunk by Greece.