In line with the law, the 27-kilometre Koper-Divača track, seen as vital for the development of the Koper port, will be built with a mix of budget funds, EU funding, contributions by landlocked countries that use the port, and special levies on port cargo and lorries.

Infrastructure Minister Peter Gašperšič has argued the international relevance of the project, pointing to letters of support from Poland, Hungary, Slovakia and the Czech Republic.

The opposition countered that the participation of hinterland countries, especially Hungary, which has reportedly also expressed its intent to invest in the special purpose vehicle 2TDK, could hurt Slovenia's interests in the long run.

As for fees, calculations by the Infrastructure Ministry show EUR 11.5m annually would be collected with lorry fees on motorways, and EUR 8.3m would come from a transshipment fee levied on the port.

The figure for the port fee is half that initially calculated by port operator Luka Koper and is the result of amendments proposed by the coalition.

The act envisages a five-member body to oversee the financial and other aspects of the project. Four members will be put forward by ministries and one by the civil society, but they will all need to be endorsed and appointed by the infrastructure minister.

The act was rushed through parliament despite protests from the opposition and stakeholders, which pointed to the possibility of calling a referendum or filing for a constitutional review of the act.

The government argued the haste was necessary to meet the 14 July deadline for applying for funding under the Connecting Europe Facility (CEF).