By Giselda Vagnoni
ROME (Reuters) - Italy called on Thursday for a funding review of a high-speed rail link with France, a multi-billion-dollar project that threatens to tear apart Rome's ruling coalition.
The Alpine rail line is backed by the ruling League party but is fiercely opposed by its coalition partner, the 5-Star Movement, which argues Italy's share of the funding would be better spent upgrading existing roads and bridges.
The TAV project (Treno Alta Velocita) is an equal joint venture between Italian and French states, with the European Union funding up to 40 percent of costs, Italy up to 35 percent and France up to 25 percent.
Italian Prime Minister Giuseppe Conte said on Thursday that recently updated traffic projections for the line warranted a review of the project's long-term viability and, if necessary, a renegotiation of the way the funding is split.
"Further (coalition) meetings will be necessary given a final agreement has not yet been reached," Conte said in a statement following talks that went late into Wednesday night between leaders of the League and 5-Star.
The ruling parties are due to meet again on Thursday to try and reach an agreed position. Conte has promised that the government will make a decision by Friday.
The right-wing League and the anti-establishment 5-Star have been at loggerheads over several major issues since forming an unlikely alliance last year after inconclusive elections. There is growing media speculation that the Alpine rail link could be the issue that finally brings it down.
Work has already started on the most ambitious part of the project, a 58km (36 mile) tunnel through the Alps.
A report commissioned by Transport Minister Daniel Toninelli, a 5-Star politician, recently found that the project was a waste of public money. The transport ministry puts the total price tag at more than 20 billion euros (£17.18 billion).
The report estimated that the economic return would be a negative balance of between 7.0-7.8 billion euros ($7.9-$8.8 billion).
(Reporting by Giselda Vagnoni; Editing by Mark Bendeich and Jon Boyle)