France and Italy on Monday vowed to press ahead with a controversial 26 billion euro high-speed rail line through the Alps despite doubts over EU financing for a tunnel at the centre of the project.
In a move intended to underline their commitment to the link, transport ministers signed a joint declaration on the financing of the 57-kilometre (35-mile) tunnel, which will account for one third (8.5 billion euros) of the total costs.
The accord provides for Italy to cough up 2.9 billion euros ($3.8 billion) of this, with France contributing 2.2 billion euros and the balance, equivalent to 40 percent of the total, coming from European Union funds allocated to strategic cross-border projects.
French President Francois Hollande acknowledged that the EU financing remained uncertain.
"For the 40 percent, France and Italy will have to continue working to persuade the European Commission," he told a press conference. "A lot will depend on the EU budget."
EU governments are currently deadlocked over the bloc's 2014-20 budget, with Britain and Germany holding out for a real-terms freeze in spending.
Italian Prime Minister Mario Monti said the project was important "not only for our two countries, but for all of Europe."
The proposed rail link would cut journey times between Paris and Milan from seven to just over four hours. It was first proposed at a Franco-Italian summit in 1991 and is officially scheduled to be finished in 2025, although officials acknowledge that 2028 is now a more realistic target.
Supporters claim it will take a million heavy lorries off roads between Italy and France and cut CO2 emissions by three million tonnes a year.
For Hollande and Monti, the project is emblematic of the pro-growth agenda they have jointly promoted within the EU.
Critics argue it could become a white elephant subsidised by unjustifiable injections of national and European funds at a time when every other area of public spending is being tightened.
It was initially supported by green groups, but they have since turned against it.
Hundreds of activists gathered Monday in Lyon to make their opinions heard, many of them from Italy where the No-TAV (Treno Alta Velocita, or high-speed train) movement has become a focus for broader opposition to the austerity programme imposed by Monti's government in response to the eurozone debt crisis.
France's public spending watchdog, the Cour de Comptes, said in a report last month that the whole project had been characterised by poor management and vague financing arrangements. It recommended that the government look again at upgrading the existing lines and tunnel.
Monday's joint declaration was intended, in part, to respond to that criticism by providing for the creation of a new management structure for the project which will be put in place next year.