The OZS said that hauliers were concerned about the delays in the construction of the tunnel caused by the National Review Commission, which had annulled the motorway company DARS's selection of Turkish contractor Cengiz Insaat Sanayi ve Ticaret to build the second tube of the tunnel.

"The Karavanke tunnel is one of the most important transport routes for merchandise, which means that every obstruction of the traffic flow causes significant damage to the economy.

"We do not understand and accept delay in building such a strategically important infrastructural object," the head of the OZS' hauliers' section Peter Pišek said.

Even now, tailbacks regularly occur at the tunnel, with transporters losing up to five hours to pass it. "Jams mean lost time, obstacles to servicing economy, negative impact on the environment and an increased risk of traffic accidents," the OZS added.

Things started to get complicated after the National Review Commission apparently excluded the initially selected contractor from the tender from the construction of the second tube upon an appeal by other applicants.

On the other hand, Cengiz has said that it was not excluded from the tender and that DARS simply has to decide anew.

However, Vili Žavrlan, a board member at DARS, told public broadcaster TV Slovenija on Sunday that Cengiz's offer could only remain in the running if similar inefficiencies were found with the other applicants.

According to the commission, Cengiz formed the prices for the project's various cost items only after it was warned about discrepancies between the total amount in its selected bid and the items detailed or absent in the bid's supplements.

Žavrlan said that a quick review of the other applications uncovered inconsistencies and that "we could come to a point where these will be inadmissible too". However he would not guess about the possibility of a renewed tender, noting that the law provided for other possibilities such as talks with the bidders too.

The entire project involves the construction of a new, 3,546-metre motorway tube and a 620-metre motorway section connecting the tube to the existing motorway.