The Croatian Ministry published the tender for gas and oil exploration in 29 blocks of the Adriatic seabed, including eight in the northern section of the Croatian part of the Adriatic Sea.

The call said that the border dispute with Slovenia is currently subject to arbitration, but included maps showing the borderline midway the Piran Bay, even though the sea border between the countries has not been drawn.

"Slovenia will closely examine the locations of the areas in the North Adriatic that the government of Croatia has envisaged for the exploration and use of gas and oil. If necessary, appropriate measures will be taken to protect Slovenia's interests," the embassy said in a press release.

The embassy noted that the countries have agreed to resolve the issue of the border and corresponding sea belts before an arbitration tribunal.

The embassy also expressed regret that the Croatian authorities have not sent Slovenia detailed information on the part of the tender pertaining to the part of the sea under dispute, despite repeated requests from Slovenia to do so.

Article 10 of the Arbitration Agreement stipulates that both parties shall refrain from any action or statement which might intensify the dispute or jeopardize the work of the arbitration tribunal.

If upon examining locations Croatia plans to offer for exploration to concessionaires, Slovenia finds the maps are in breach of the Arbitration Agreement, this would be the first such violation after the countries signed the accord in Stockholm in November 2009.

The oral hearing before the tribunal is set to begin in the first half of June.