DARS had been asked to review its decision by Nova Gorica-based Kolektor CPG as well as by the local builder Gorenjska Gradbena Družba, which has partnered with Czech builder Metrostav.

Both are among the six bidders DARS wants to engage in negotiations for the Slovenian section of a second tube of the 7,948 metre tunnel, whose construction on the Austrian side has been under way since September last year.

According to unofficial information, the two builders will formally be notified of the rejection by post today, as will the Review Commission, which could adopt a decision before May.

After appeals by two bidders, the Review Commission annulled last November DARS's decision to select Turkish builder Cengiz, arguing its EUR 89.3m bid had been changed during the selection process.

Establishing that none of the originally filed bids had been fully compliant with the project demands, DARS decided last month to select the contractor through negotiations.

It invited Cengiz alongside Austria's Implenia Österreich, Slovenia's Gorenjska Gradbena Družba and Kolektor CGP, Bosnia's Euroasfalt and Greek J&P Avax.

The Slovenian and Austrian sides planned to "meet" at the border, or roughly in the middle of the tunnel, in 2022.