A press release issued on behalf of the tribunal by the Permanent Court of Arbitration said that the tribunal had informed Slovenia and Croatia by letter on 29 March that there was no need for any further submissions from the parties in respect of the merits of the case.

"The tribunal thus declared the hearings closed in accordance with the applicable rules of procedure. The tribunal further indicated that it planned to render a final award in the proceedings in the coming months."

The specific date for announcing the final decision would be made known in due course.

In line with the 2009 arbitration agreement, the tribunal is to set the border between Slovenia and Croatia at both land and sea.

Croatia, which agreed to the framework of the arbitration to have Slovenia unblock its accession to the EU, withdrew from the process in 2015 after Croatian media released on 22 July leaked phone calls between the Slovenian arbiter Jernej Sekolec and the country's agent in the process Simona Drenik.

Prime Minister Andrej Plenković repeated Croatia's position today, saying that the tribunal's decision would not be binding for Croatia, as its parliament confirmed the country's withdrawal from the procedure in 2015.

"A solution to the issue of land and sea border with Slovenia is yet to be reached," Plenković told reporters in Zagreb.

The announcement from The Hague comes after two Croatian dailies reported today that the tribunal had made its decision and would announce it shortly, possibly as early as in the next few days.

Citing unnamed diplomatic sources, the Jutarnji list paper reported that the award would be similar to the solution planned in the 2001 agreement between the then PMs Janez Drnovšek and Ivica Račan.

The agreement, which was never implemented because it was not ratified by Croatia, allotted most of the Piran Bay to Slovenia, while leaving Croatia direct border with Italy.

The paper also linked the arbitration process to the long tailbacks of traffic on the Slovenian-Croatian border that were generated after EU-imposed stricter check-ups.

Similarly, another Croatian paper Novi list suggested that the already tense relations between Slovenia and Croatia were about to deteriorate.

The Slovenian Foreign Ministry responded by saying they had no information backing the media reports and would not comment because the arbitration process was on-going and confidential.

Slovenia and Croatia resorted to international arbitration after failing to resolve their border dispute stemming from the 1991 break-up of the former Yugoslavia.

In 2009, the two countries signed the arbitration agreement under the auspices of the Swedish EU presidency tasking an international tribunal to set the course of the border, most notably in the disputed Bay of Piran.