Luxury shoemaker Tod's threatened on Thursday to scupper a multi-million euro restoration deal for Rome's crumbling Colosseum after its sponsorship of the scheme came under scrutiny from regulators and unions.

Diego della Valle - Foto APCOM

Italy's antitrust body is looking into a deal which grants Tod's exclusive rights to the Colosseum's logo and images for 15 years in exchange for 25 million euros ($31.99 million) to fund much-needed repairs to the crumbling 2,000-year old monument.

The deal has also been criticised by a trade union and a consumer group, who have both turned to the courts in an effort to stop the project.

"If somebody can do better than us, he's welcome," Tod's founder Diego Della Valle told reporters in Rome. "We are available only if the operation is crystal clear and as long as it's done quickly, otherwise we will step aside."

Culture Minister Lorenzo Ornaghi said in a statement on Thursday that della Valle had said he intended to pull out of the campaign, the biggest to repair Italy's neglected archaeological treasures with private money, but was asked to reconsider.

The contract allows Tod's to put its brand on tickets to the imposing Roman monument and at the working site. Della Valle, who also funds Milan's La Scala opera house, reiterated on Thursday that his company would not use its sponsorship of the restoration for commercial purposes.

Sponsorship of the arts was for decades anathema in Italy, but economic hard times have forced governments to go cap in hand to the private sector for help to care for the wealth of ancient treasures spread across the country.

Tod's, which makes luxury shoes and leather bags, emerged last year as the only private sponsor willing to fund the Colosseum project, after a tender fell through. The deal was presented to the press with great fanfare a year ago.

The 80 A.D. Roman amphitheatre, which housed bloody public spectacles including gladiator fights, mock sea battles and animal shows, attracts 6 million visitors each year.

But like other world-class archaeological sites in Italy, including Pompeii, its upkeep has suffered badly in recent years due to a lack of funds.

($1 = 0.7814 euros) (Reporting by Antonella Ciancio, editing by Paul Casciato)