Most companies in landlocked Hungary use the port, on the Adriatic, for their sea cargo transport.

According to Slovenian government plans, total investment in the 27 km line will cost about 1 billion euros..

"We have been negotiating Hungarian contribution of about 200 million euros which seems to be realistic but ... details have not been clarified yet," Szijjarto told a news conference during a visit to Slovenia on Thursday.

Three quarters of the new line will run underground. It should significantly increase the capacity of the port, which lies about 310 km from Slovenia's border with Hungary.

Szijjarto said Hungary did not expect to get a stake of Luka Koper in return for its investment, saying Slovenia has made it clear it plans to keep it in the hands of the Slovenian state.

He said, however, Hungary hoped that its companies would get a prioritised approach to the port, possibly by a long-term leasing or rental contract, while Hungarian companies could also get work on the construction of the railway, giving no details.

He also said all cargo transport from Koper to Central Europe could go through Hungary so that Hungarian cargo firms would benefit from the project.

Slovenia hopes to cover about a quarter of the whole investment with European Union funds while about 350 million euros will be raised via new debt. The investment will be one of the biggest in Slovenia in the coming years.

Reuters