The meetings are expected to revolve around the implementation of the border arbitration decision, which Croatia refuses to honour, Slovenia's roles in the EU and NATO, and its role in the Western Balkans.

In his address to Slovenia's diplomatic corps last week, the president said that the key message of his visit to Brussels will be that the border arbitration decision can be implemented through patient dialogue.

This will however require a message from the Croatian government that it accepts certain parts of the border, and government talks about the final border demarcation, as well as a more active role of the European Commission in this process, he told the diplomats at their annual meeting.

Pahor believes that a delay in implementation could have a negative effect on bilateral relations between the two neighbouring countries, which in turn could affect the atmosphere in the Western Balkans in general.

The European Commission did not comment on the expected topics of the meetings, saying only that such meetings never have a set agenda and that Tusk and Junker will discuss topical issues that concern the bloc and Slovenia.

NATO sees Pahor's visit as an opportunity to exchange opinions about the security situation in the Western Balkans and discuss the preparations for the upcoming NATO summit.