Croatia and Slovenia failed on Wednesday to reach an agreement on implementing an international arbitration ruling in a long-standing border dispute that has caused tensions between the European Union neighbors.

The Slovenian and Croatian prime ministers, Miro Cerar and Andrej Plenkovic, met for the first time since The Netherlands-based panel in June granted Slovenia unhindered access to the Adriatic Sea and ruled on several other disputed border issues stemming from the breakup of Yugoslavia in the 1990s.

Plenkovic reiterated that Croatia will not implement the arbitration court's decision and insisted that territorial issues should be resolved between the two states.

"For Slovenia, the ruling of the Arbitration Court is final and obligatory," Cerar said. "It is important that both sides respect the border line determined by the Arbitration Court."

He said Slovenia is "likely" to turn to the European Commission, EU's executive body, to help the implementation of the ruling.

The two countries had agreed to arbitration in 2009, after which Slovenia dropped its opposition to Croatia's EU membership. Claiming violations of the tribunal rules by Slovenia, Croatia walked out of the process in 2015 and does not recognize its findings.

"The arbitration process was contaminated and corrupted," Plenkovic said. "And this is the reason why Croatia left the arbitration process."

Both prime ministers said the dialogue will continue.