Austria has threatened to use its veto to block further talks on Turkish membership of the European Union, deepening the stand-off with Ankara over President Recep Tayyip Erdogan’s crackdown on democratic freedoms.

The move could jeopardise the EU’s controversial migrant deal. Turkey has already threatened to pull out of the agreement, potentially sending hundreds of thousands of asylum-seekers to Europe.

Sebastian Kurz, the Austrian foreign minister, said he would veto any attempt to open a new chapter of accession talks with Turkey — effectively blocking the country’s path to possible membership.

“I have a seat and a vote in the council of foreign ministers, where it will be decided if a new chapter will be opened with Turkey. And I am against it,” Mr Kurz wrote in an article for Austria’s Kurier newspaper.

Any decision by the council on EU accession talks has to be agreed unanimously by all current member states.

A new round of talks on eventual Turkish membership was one of the conditions for the migrant deal, under which Turkey agreed to prevent asylum-seekers entering Europe and accept those deported from Greece.

The Turkish government has already threatened to withdraw from the agreement if its citizens are not granted visa-free travel to the Schengen Area by October.