At least 435 irregular migrants were held in the Turkish metropolitan city of Istanbul, according to security sources on Thursday.
Police carried out operations in Beylikduzu, Fatih, Kucukcekmece, Buyukcekmece, Zeytinburnu, Gungoren, Maltepe and Esenyurt districts.
The irregular migrants from 24 countries, including 145 from Syria and 135 from Afghanistan, either illegally entered Turkey or their visas expired, and their deportation process is underway.
Turkey has been a main route for irregular migrants trying to cross to Europe, especially since 2011 when the Syrian civil war began.
It hosts nearly 4 million refugees, including over 3.6 million Syrians, more than any other country in the world.