“Not building the high-speed line would cost much more than building it,” Conte said in an address posted on his Facebook page. “The decision not to carry out the work would expose us to costs resulting from breaching our agreement with France.”

The Lyon - Turin project is a source of contention within Italy’s coalition government. The League is in favour of moving forward with construction, while the populist Five Star Movement, the party of transport minister Mr Danilo Toninelli, has been pushing for its cancellation.  

On July 23, deputy prime minister Mr Matteo Salvini urged Toninelli to “unblock” the project.

Conte says the European Union (EU) will increase its contribution from 40% to 55% of the project’s €25bn cost. The European Commission has previously threatened to cancel grant funding already allocated to the project due to the political impasse.

The 270km line will include a 57.5km twin-bore base tunnel between St Jean de Maurienne, France, and Chiomonte in Italy.

Implementation of the project is being managed by Euralpine Tunnel Lyon - Turin (TELT), a 50:50 joint venture between Italian State Railways (FS) and the French state. Conte instructed TELT to suspend tendering for the project in March.