FILE PHOTO - A view of Slovenian city Portoroz and Piran/Savudrija bay from Croatian village Kanegra, Croatia, June 28, 2017. REUTERS/Antonio Bronic

BRUSSELS (Reuters) - The European Union’s top court ruled on Friday that it had no jurisdiction to settle a border dispute between Slovenia and Croatia, complicating Croatia’s accession to the Schengen free-travel area.

Slovenia had argued that its fellow EU member could be sued under EU law because it was not implementing a 2017 border ruling by the intergovernmental Permanent Court of Arbitration in The Hague.

The European Commission has said Croatia meets the technical criteria for Schengen membership, but Slovenia is unhappy with Croatia’s rejection of the ruling, and has the power to veto its accession.

“The Court of Justice of the European Union lacks jurisdiction to rule on a border dispute between Slovenia and Croatia,” the court said, adding that the two states were required to find a solution between themselves.

The two Balkan countries have argued for years about the course of their land and sea border at Piran Bay on the Adriatic Sea.