European Commission President Jean-Claude Juncker agreed that "Turkey cannot become a European Union member in its current state".

But he rejected the Austrian position. "I don't think it would be helpful if we were to tell Turkey unilaterally that the negotiations are over," he told German ARD news.

Freedom of movement

In 2005 Turkey began negotiations to join the EU, but progress has been extremely slow. Many European politicians are against Turkey joining, although it is an official candidate.

Turkey has urged the EU to grant visa-free travel to Turks wishing to visit the Schengen zone, covering most of Europe.

The EU offered visa liberalisation as part of itsMarch dealwith Turkey, aimed at curbing the flow of migrants from Turkey to Greece.

But the EU attached stringent conditions to the travel offer - and so far, the EU says, Turkey has only fulfilled some of them.