The CJEU said it lacked jurisdiction over the case as it concerned matters outside the EU's powers. | John Thys/AFP via Getty Images EU top court says it can’t rule in Slovenia-Croatia border dispute Two governments must work to end standoff, judges declare.

The Court of Justice of the European Union today called on Slovenia and Croatia to "strive sincerely" to resolve their border dispute as it declared it lacks jurisdiction to rule on the matter.

The two neighboring EU countries, which emerged from the breakup of Yugoslavia in the 1990s, have been embroiled in a long-running quarrel that also affects fishing rights.

The matter was meant to be settled by arbitration in The Hague but Croatia withdrew from the process, accusing Ljubljana of fatally undermining it, before the international tribunal ruled in Slovenia's favor in 2017. Croatia refused to implement the ruling, prompting Slovenia to send a complaint to the EU's top court.

But in a press release on Friday, the CJEU said it lacked jurisdiction over the case as it concerned matters outside the EU's powers.

The court added that the two countries had a duty under the bloc's treaties "to strive sincerely to bring about a definitive legal solution consistent with international law, in order to ensure the effective and unhindered application of EU law."

The standoff has prompted top EU officials to state that the bloc will not admit any more countries that have outstanding territorial disputes — a message to would-be members from the Western Balkans such as Serbia and Kosovo, who have yet to reach a permanent settlement after their war in the late 1990s.