A marble elephant designed by Baroque master Gian Lorenzo Bernini has been damaged, with its left tusk found snapped off and lying at the base of the monument in the heart of Rome, authorities said.

The damage was uncovered on Monday night and police said they would review video footage from Piazza della Minerva to determine whether the tusk was vandalised or simply fell off following weeks of unusually heavy rains.

Italy's Culture Minister Alessandro Giuli made clear he thought it was deliberate, saying the 17th statue, which supports an ancient Egyptian obelisk, was victim of an "absurd act of barbarity".

"It is unacceptable that once again the nation's artistic and cultural heritage must suffer such serious damage," he said in a statement.

It is not the first time the sculpture, popularly known as the Elefantino (little elephant), has been damaged.

In November 2016, the tip of the same tusk was similarly found broken off. The piece was reattached during restoration work.

The sculpture, created in 1667 by Ercole Ferrata based on a design by Bernini, stands a short distance from the Pantheon, one of most visited tourist sites in Rome.

-Reporting by Francesca Piscioneri, editing by Crispian Balmer/Reuters