Janša confirmed that the government considered two proposals that define the subject matter of arbitration, recommending that the proposal prepared by the Foreign Ministry task force be "slightly modified" with "proposal B".

While he did not specify what "proposal B" is, it is believed to be documents prepared by Institute 25 June, a patriotic outfit, which had also been submitted to the Foreign Policy Committee earlier this week.

Media reports suggest that the alternative proposal involves arguing for a border on the cape of Savudrija, which was historically part of the Piran municipality.

Parliament will thus be asked to decide "between the baseline variant and the minimally supplemented variant in a time frame that will make this minimal correction possible".

The reason why parliament is being asked to weigh in is "purely formal": in 2009 the National Assembly adopted a resolution on the protection of Slovenia's interests and the government "cannot bypass" it, according to Janša. "Only parliament can override the resolution."

The parliament resolution, which was adopted with a two-thirds majority, states that Slovenia "rejects attempts at violation of Slovenia's territorial integrity".

It mentions that Slovenian authorities exerted jurisdiction on the left banks of the Dragonja (W) and Mura (E) and "over the entire Bay of Piran".

This was the third time that the government had the issue on the table, but Janša said it had previously only been given a report by the task force.

There were complaints with regard to the report, but "the problem was much smaller than reported, he said, noting that the report had not been "in accordance with the appendices and maps".

Deputy Speaker of Parliament Jakob Presečnik told the STA that the extraordinary session of parliament could be held on Monday provided he receives the formal request today.

Foreign Minister Karl Erjavec refused to comment on the development, but the decision was criticised by the opposition Positive Slovenia (PS) and Social Democrats (SDS).

PS lawmaker Janja Klasinc, the vice-chair of the Foreign Policy Committee, said the government's conduct was "unacceptable and unserious". "I don't know what they are opening again," she added.

SD deputy group leader Janko Veber meanwhile noted that the arbitration agreement stipulated that the government needed to confirm the memorandum.

"Everything else is exploitation of this important issue for daily politics, which is unpatriotic and unserious," he said.