"I am very satisfied with the verdict saying that the agreement is in line with the Constitution," Pahor said after the announcement of the ruling.

He added that he would begin consultations first with partners in the ruling coalition and later with the Opposition on further steps which would make it possible for the Slovenian parliament to ratify the agreement, signed by him and his Croatian counterpart Jadranka Kosor in Stockholm last November.

In order to accelerate the ratification procedure, Pahor suggested that parties of the ruling coalition could withdraw their motion from the parliament's agenda on holding an advisory referendum on the matter.

That way, Slovenian lawmakers could discuss the ratification bill without that consultative referendum.

Later in the day, Slovenian Foreign Minister Samuel Zbogar said that his country could continue with preparations for arbitration and that he expected the Slovenian parliament to ratify the arbitration deal soon.

"We are now working intensively on preparing our arguments for the arbitral tribunal," Zbogar told reporters in Ljubljana.

Now that the Constitutional Court has handed its ruling, the Slovenian Foreign Ministry can resume preparations for launching the arbitration procedure, and the ministry's groups will draw up a memorandum which Slovenia will present before the arbitral tribunal, according to Zbogar.

The agreement, signed by Pahor and Kosor, provides for the establishment of an international arbitral tribunal to determine the course of the border at sea and on land, Slovenia's contact with the high seas and the use of relevant maritime areas.

The arbitral tribunal could begin operating at the start of 2011, after Croatia signs the accession treaty with the European Union, Zbogar said today.

The arbitration agreement was signed in Stockholm on 4 November and Croatia's parliament ratified it later that month.