Turkey is accusing Greece of not properly dealing with the asylum status of migrants. Instead, Turkish Interior Ministry files claim that Greece illegally transported 58,283 people to Turkey in the 12 month period leading up to November 1, 2018.
Greece is disputing the accusations, with Prime Minister Kyriakos Mitsokasis saying Ankara was playing games: "Those people who have used the refugee crisis to their own ends should be more careful when dealing with Greece."
A Greek Foreign Ministry spokesman told German news agency dpa that Athens had denied similar accusations "many times" already.
This so-called "push back" of asylum seekers is illegal under European and international law. The state is obliged to assess the asylum status of new migrants rather than sending them to another country.
Read more: Opinion: EU needs a clear refugee policy
Where were the migrants from?
According to the Turkish documents, the largest proportion of migrants sent away from Greece were Pakistani, with large numbers from Somalia, Algeria and Bangladesh. 4,500 were Syrians.
Turkish officials said they sent back most of the people back to their countries of origin except for the Syrians, who were sent back to the Turkish town where they originally registered as refugees.
The governor of the Turkish-Greek border region of Edirne reported that over 90,000 migrants were arrested between January and September 2019, a big increase from the 30,000 arrested in the same region in 2016.