France’s national rail operator SNCF has ordered trains for an Italy-bound route which reportedly turned out to be a few millimeters too high for Italian tunnels, leaving passengers to Italy having to change trains at the border.

Regio 2N trains were ordered by SNCF from Bombardier, the Canadian multinational aerospace and transportation company.

They are supposed to operate on the TER (Transport Express Regional) line that serves the French Riviera coastline between Les Arcs - Draguignan station in Provence-Alpes-Côte d'Azur region in southeastern France and the city of Ventimiglia in northern Italy, which borders on France.

The trains were delivered in November 2014 but they didn’t come into service as they turned out to be a few millimeters too high for Italian tunnels, Nice Matin newspaper reported, citing former railway workers group "The shipwrecks of the TER."

Eric Sauri, president of the group, told the paper that the SNCF confirmed that the Regio 2N trains “would not go further than the town of Menton because they did not pass under the tunnels."

Nice: trop hautes, les nouvelles rames TER ne peuvent passer en Italie via @bfmtvhttp://t.co/D1fcvvB1ad — Eric SAURI (@naufrager000) July 2, 2015

The French town of Menton is 9km from the scheduled final point of Ventimiglia. Thus, many passengers who travel further will have to change trains.

However, SNCF chief executive Guillaume Pepy said there are no grounds for concern, adding that the new trains are scheduled to operate from July 5.

"When you put something into service, sometimes it's necessary to take a look at it, there may be a signal problem here, or the start of a platform that is troublesome. But it can all be easily dealt with," he said.

In a July 2 press release, SNCF said that 10 new Regio2N trains “will travel to Ventimiglia in the month of December 2015.”

“Ventimiglia tunnel's infrastructure will have been adapted by SNCF network and the Italian network operator. This work is done according to the agreed schedule …. Similar work has already been done to adapt the network to Toulon, Cannes and Menton.”

READ MORE: French company orders $20bn worth of trains too wide for platforms

This is not the first ‘rail fail’ by SNCF. In May 2014, a blunder led to SNCF facing public humiliation and $100 million in losses after it mistakenly ordered 2,000 new trains at a cost of $20 billion that were too wide for some platforms.