NATO member Turkey has blocked a plan which would have allowed the alliance to work directly with the European Union in Kosovo, leaving the functioning of international organizations in the region in doubt, sources said Thursday, according to dpa. Under a complex compromise proposed by UN Secretary General Ban Ki-Moon on Thursday morning, NATO's 15,700-strong KFOR peacekeeping force is meant to guarantee security in Kosovo once the newborn country's constitution comes into force on Sunday. An EU mission, EULEX, is meant to provide civilian law and order from the same date, taking over from the UN mission which has performed that function hitherto. KFOR and EULEX are therefore expected to work together as the military and civilian arms of security in the new country. But on Thursday, at a meeting of NATO defence ministers in Brussels, Turkey said that it would not allow the alliance to change KFOR's operational plan so that the force could officially work directly with EULEX, sources within the alliance said. Turkey, which is a member of NATO but not the EU, is involved in a long-running dispute with Cyprus, which is a member of the EU but not NATO, over the political status of the divided island. The situation has long created tensions between the EU and NATO, even though the two bodies have 21 members in common. Cyprus refuses to allow Turkey to join the EU's European Defence Agency, a body which is meant to streamline EU defence procurement and planning, since it fears that this would give Turkey access to its military secrets. Turkey has replied by refusing to approve a closer NATO engagement with the EU - a body which it hopes to join within the next decade.