ISTANBUL — Turkey said Friday that it would begin sending captured Islamic State militants to their home countries in 72 hours, part of an effort aimed at pressuring reluctant European states to take back citizens recruited by the violent extremist group.

“Now we are telling you that we are going to send them back to you,” the Turkish interior minister, Suleyman Soylu, said in announcing that the repatriations would start on Monday. Turkey, he said in comments last weekend, was “not a hotel” for Islamic State detainees from other countries.

He did not explain precisely how they would be returned or what would happen if their home countries would not accept them. It was also unclear how Turkey would be able to legally repatriate those whose citizenship has been nullified by their home countries.

Turkey has captured several hundred people affiliated with the Islamic State over the last month as its forces seized a pocket of territory in northeastern Syria, forcing Kurdish forces there to abandon several towns and at least one detention camp. Mr. Soylu told reporters that Turkey had captured 287 Islamic State members, including women and children, during the operation.