ANKARA — Turkish President Recep Tayyip Erdogan on Tuesday issued a veiled threat suggesting Turkey could release the Islamic State group prisoners it holds and send them to Europe, angered at a EU decision to impose sanctions on his country over its drilling for gas in Mediterranean waters off Cyprus.

Speaking to reporters before a visit to the United States, Erdogan also said Turkey would continue repatriating foreign Islamic State militants to their home countries, even if those countries decline to take them back.

“You should revise your stance toward Turkey, which at the moment holds so many IS members in prison and at the same time controls those in Syria,” Erdogan warned European nations, a day after the EU unveiled a system to sanction Turkey.

He added: “These gates will open and these IS members who have started to be sent to you will continue to be sent. Then you can take care of your own problem.”

Erdogan’s comments came as Turkey launched a new push to send back captured foreign fighters to their home countries, telling Western nations that Turkey was not a “hotel” for IS fighters and criticizing them for their reluctance to take back citizens who had joined the ranks of the extremist group as it sought to establish a “caliphate” in Iraq and Syria.

Turkey deported citizens of the United States, Denmark and Germany on Monday and announced plans to soon expel seven other German nationals, two Irish nationals and 11 French nationals.

Turkey said last week that about 1,200 IS militants were in Turkish prisons and 287 IS members, including women and children, were captured during Turkey’s offensive in Syria, launched last month.

The latest spat with the EU is over exploration for gas around EU member Cyprus. Turkish drillships, escorted by warships, began exploratory drilling this summer in waters where Cyprus says it has exclusive economic rights. Turkey says it is protecting its rights and those of Turkish Cypriots on the divided island.

EU foreign ministers adopted a mechanism making it possible “to sanction individuals or entities responsible for, or involved in, unauthorized drilling activities of hydrocarbons.” EU member countries can now come forward with names of those they think should be listed.

While Turkey has quietly deported IS sympathizers for years, it raised the issue more forcefully after Western nations refused to back its offensive against Syrian Kurdish fighters whom Ankara considers to be terrorists linked to Kurdish militants fighting inside Turkey. Many countries have voiced concerns that the Turkish incursion would lead to a resurgence of IS.

Turkish news reports said Monday that a U.S. citizen who had been deported by Turkey was stuck in a heavily militarized no man’s land between Greece and Turkey, after Greece refused to take him in.

Asked to comment on the reports, Erdogan said: “Whether they are stuck there at the border it doesn’t concern us. We will continue to send them. Whether they take them or not, it is not our concern.”