Austria is threatening to sabotage the hard-won Macedonia name deal unless the European Union ends membership talks with Turkey, in the latest sign of deep divisions in a bloc riven with discord over migration.

Greece and Macedonia took a major step towards ending almost 30 years of bitter dispute on Sunday, as the countries signed an accord that will rename the Balkan nation the Republic of North Macedonia in return for Athens promising not to block Skopje’s efforts to join the EU.

The breakthrough was accomplished amid suspicions that the Former Yugoslav Republic of Macedonia coveted the Greek region of Macedonia. But the deal could now be derailed in Brussels at a June 28 summit of EU leaders, EU diplomats told The Telegraph.

Every European Council summit usually ends with the publication of a set of conclusions, which act as political instruction to the European Commission.

Austria has informed diplomats in Brussels that it will scupper any conclusions on EU enlargement, if Turkey is mentioned alongside Macedonia and the Western Balkans countries such as Serbia and Montenegro that hope to eventually join the bloc.

“Austria has told us they will block the Council conclusions over Turkey,” one EU diplomat said. A single country blocking conclusions is not unprecedented but it is rare and usually only a last resort.