Turkish contractor Cengiz currently has 43 workers on site, a figure that is set to increase to 150 when boring is ramped up to a 24/7 cycle, according to Valentin Hajdinjak, the chairman of motorway company DARS.

Both Hajdinjak and Asim Cengiz, a member of the Cengiz board, told the press on Friday that the project, valued at just under EUR 100 million, will be completed on schedule and on budget. "Cengiz plans to complete the works before 2025," Asim Cengiz said.

Infrastructure Minister Jernej Vrtovec said this was "a great day for Slovenia, for the entire logistics sector and for neighbouring countries."

He also expressed the wish that Cengiz enlist as many Slovenian subcontractor as possible, which he said he had also briefly discussed with the company's representatives.

The boring starts two and a half years after DARS issued a public call. It took until 22 January this year before the contracting procedure was completed.

The second tube of the motorway tunnel is just under eight kilometres long, with the Slovenian section measuring 3.5 kilometres. On the Austrian side boring is well under way.