Cerar cancelled the 27 September visit to Croatia after Andrej Plenković, the Croatian prime minister, offered in his address to the 72nd session of the UN General Assembly the arbitration tribunal's decision on the border between Croatia and Slovenia as an example of how international law is being undermined.

Slovenian President Borut Pahor labelled the stance as unacceptable and said Croatia was "stubbornly insisting" on rejecting the arbitration tribunal's decision.

The speech also prompted a stern rebuke from parliamentary Speaker Milan Brglez, who described it as "inconceivable".

He also accused Plenković of having abused the organisation and questioning "the fundamental principle of the peaceful resolution of dispute in front of all countries of the world".

Both stressed that dialogue was still the only way to resolve the dispute, but Brglez added the caveat that "the ball is now in Croatia's court".

Foreign Minister Karl Erjavec likewise endorsed Cerar's decision, but he suggested that given Croatia's track record, dialogue was not possible at this point.

"All those politicians who have favoured dialogue with Croatia got proof in New York that this dialogue is impossible," Erjavec told the STA.

He announced the Foreign Ministry would instruct all Slovenian diplomats abroad to inform the foreign ministries of the host countries about the reasons for the cancellation of Cerar's visit.

Most parliamentary parties expressed support for the move and said that Slovenia needed to continue with preparations for the final implementation of the tribunal's award before the end of the year.

The chair of the parliamentary Foreign Policy Committee, Jožef Horvat of the opposition New Slovenia (NSi), said that the committee would continue to discuss the arbitration issue next week, regardless of whether the government prepares all the necessary documents.

Three months have passed since the arbitration ruling was declared [on 29 June] and the country has only three more months to adjust its legislation, he noted.

But party officials also levelled criticism at Cerar.

The head of the opposition Democrats (SDS), Janez Janša, eschewed commenting, but said on Twitter that Croatia was playing cat and mouse with the Slovenian prime minister.

The head of the group of unaffiliated MPs, Bojan Dobovšek, said Cerar's problem was inconsistency and lack of skill to advocate Slovenia's case in the international community.

And one party, the Left, said Cerar's move was hasty since Plenković merely reiterated Croatia's long-held position.

Plenković said in his speech that treaties and arbitration processes were only legitimate if they were conducted in line with rules.

"Compromising the impartiality or independence of international adjudicators and tribunals as was the case in the terminated arbitration process between Croatia and Slovenia makes their decision legally void," he said.

Cerar called off the visit just two days after he and Plenković held a brief meeting on the margins of the UN General Assembly and agreed to meet in Zagreb for talks focused on arbitration.

He had previously said he would not meet Plenković unless the implementation of the arbitration tribunal's award, which Croatia does not recognise, was on the agenda.