Turkey said Monday it would send ISIS prisoners back to their countries of origin, regardless of whether they had been stripped of citizenship.
Interior Minister Soleyman Soylu said Turkey had nearly 1,200 foreign members of ISIS in custody, and had captured 287 during its recent operation in northern Syria.
"Of course, those that are in our hands, we will send them back to their countries," he said, according to state news agency Anadolu.
"However, the world has devised a new method. They say, 'Let's strip them of their citizenship … Let them be tried where they are'.
"It is impossible for us to accept this view … We will send [ISIS] members to their countries whether they strip them of their citizenship or not.
“Turkey is not a hotel for ISIS members of any country."
It is not known whether Turkey will be able to do so in practice.
Western countries have often refused to accept the repatriation of citizens who left to join ISIS in Syria, and have stripped many of their citizenship.
Under the New York Convention of 1961 it is illegal to leave someone stateless, but several countries, including Britain and France, have not ratified it, and recent cases have triggered prolonged legal battles.
The UK has stripped more than 100 people of their citizenship for allegedly joining militant groups abroad.
High-profile cases such as that of teenage ISIS recruit Shamima Begum and alleged recruit Jack Letts, also known as "Jihadi Jack", have sparked court proceedings and fierce political debate.
On Monday Turkey requested that Germany repatriate 20 of its fighters, in total 80 of its nationals are being detained.
It said four of the German ISIS fighters have been captured since the Turkish military offensive in northeast Syria launched in October and the other 16 were already in Turkish custody.
In a policy document published last month on the issue, Anthony Dworkin, a senior policy fellow at the European Council on Foreign Relations, called on EU countries to end their “policy denial” and start repatriating detained ISIS supporters.
He wrote: “European countries should end their policy of denial and look for the first available opportunity to start repatriating detained ISIS supporters from Syria. Doing so offers numerous advantages, providing ways of: distinguishing between the different categories of European ISIS supporters; establishing their responsibility for specific crimes through fair and well-conducted trials; and using the information they possess to learn more about ISIS.
“The potential threat that returnees could pose, and difficulties in prosecuting them, may well be exaggerated, and ways exist for European governments to mitigate them.
“Repatriation would also be the fastest way to move detainees out of the situation of instability they currently find themselves in. It would limit both the risk of losing control of committed ISIS supporters and the harm that delay is inflicting on hundreds of children.”