Athens says it had blocked the largest single migrant crossing attempt this year.
The Greek coast guard said on Monday it had prevented hundreds of would-be migrants and asylum seekers from crossing the Aegean Sea from neighbouring Turkey.
Five sailing boats and four dinghies that had all left the Turkish coast on Monday morning were intercepted in Turkish territorial waters near the Greek islands of Chios and Samos.
"Greek patrol boats were able to quickly locate the vessels and inform the Turkish coastguard," a spokesperson told AFP.
In a statement, the coastguard added: "The total number of people on board the nine boats and dinghies is said to exceed 590."
Port police said on Tuesday they had prevented another 150 more people from entering Greek waters. The authority said it had intercepted four dinghies "using sound and light signals, alerting the Turkish authorities".
Athens has regularly accused Ankara of failing to prevent smugglers from trafficking would-be migrants and asylum seekers into Greece, in violation of a 2016 agreement with the European Union.
But NGOs have also long accused Greek authorities of illegally pushing migrants back into Turkey. The Greek government has always denied the allegations and recently stepped up border control around the country's islands.
"We are taking all appropriate measures to protect Greece's and the EU's maritime borders while respecting international law and human life," the coastguard said on Monday.