BRUSSELS (AP) — European Union foreign ministers expressed fresh concern Monday about Turkey's crackdown on political opponents and the media, while President Recep Tayyip Erdogan suggested he might call a referendum next year on whether his country should join the bloc. At talks in Brussels, the ministers struggled to forge a common stance that would balance their desperate need for Ankara's help to stop hundreds of thousands of refugees heading to Europe with deep concerns about rights abuses in Turkey in the wake of the thwarted military coup in July. Earlier, Turkish media reported that police had detained a group of students who protested Erdogan's move to appoint a president to head Istanbul's prestigious Bogazici University. [...] after years of foot-dragging by some countries, the EU has promised faster membership talks, visa-free travel for Turkish citizens and billions of euros in aid for Syrian refugees living in Turkey if Ankara stops migrants setting off for Greece and agrees to take back thousands of others.