Italy’s culture ministry is playing down reports that chunks of masonry have been falling off the Colosseum, Rome’s most popular tourist attraction.

On Christmas Day, tourists found small fragments of tufo, the porous rock typical of ancient Roman monuments, on the ground, prompting fears the 2,000-year-old structure was crumbling.

There were further reports of falling masonry on Tuesday, and the culture ministry issued a statement saying that “nothing has collapsed” at the Colosseum “since the 18th century.”

Italy said it was investigating the reports, while the manager of the Colosseum denied there were problems.

"There is a psychosis of collapse. It's something that happens. It's already happened before,” Rossella Rea was quoted as saying.

Italian environmental group Legambiente has frequently raised the alarm about the effect of car exhaust and vibrations from the nearby subway on the Colosseum.

Lobby groups have also criticized the cash-strapped government for cutting spending on upkeep of its archeological sites.

The site of ancient gladiator contests is to undergo a €25 million ($33-million US) restoration, paid for by Diego Della Valle, founder of shoemaker Tod's. That restoration is scheduled to begin in March, but the Colosseum will remain open to tourists.

With files from The Associated Press