European Commission President Jean-Claude Juncker says Turks will only be granted visa-free travel to EU countries from October if Ankara meets all the requirements, including reforming anti-terror laws.
Earlier this month, Turkish Foreign Minister Mevlut Cavusoglu said his government could stop helping to stem the flow of refugees and migrants to Europe if the 28-nation bloc failed to relax travel rules for Turks from October.
His comments coincided with increased tensions between Brussels and Ankara following the failed July 15 coup in Turkey.
Europe has been alarmed by a crackdown since the coup and has long worried that Turkey's anti-terrorism laws are applied too broadly to quash dissenters and critics of President Tayyip Erdogan.
"The question of visa-free travel, which is directly connected to the agreement on handling refugees, can be implemented on October 1 only if all the conditions are met," Juncker told the European Alpbach forum, an annual conference in Austria.
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"Anti-terror laws cannot be used to imprison intellectuals, scientists and journalists. That is not the fight against terror that we mean," he added.
Brussels wants Turkey to soften the legislation but Ankara has refused, saying the laws are vital to fighting Islamic State and Kurdish militants.
Turkey, meanwhile, is furious over the EU's cautious response to the failed putsch, in which 240 people were killed.
Since the coup, more than 17,000 people have been placed under formal arrest, and tens of thousands more suspended from their jobs. Turkish authorities blame the failed putsch on US-based Muslim cleric Fethullah Gulen and his followers.
Gulen denies involvement and has condemned the coup attempt.
