A 22-year-old German man has been detained in Florence accused of damaging a statue in the 16th-century Fountain of Neptune in the Piazza della Signoria, city authorities said in a statement.

The city estimates the damage to the statue is around €5,000 ($5,400).

The fountain features a statue of the Roman sea god Neptune atop a shell-shaped carriage pulled by horses.

The tourist, who has not been named, scaled a protective barrier around the monument in the early hours of Monday and posed on the statue while two friends, who remained on the other side of the barrier, took photos of him, the city statement said, citing police officers who witnessed the event on surveillance footage.

"According to the investigators' reconstruction, after 1 o'clock this morning the tourist, in Piazza della Signoria with two other friends, climbed over the fence of the Neptune Fountain and climbed onto the edge of the pool," the statement said.

"With a jump he then climbed onto the horse's leg, reaching the base of the carriage and, after having some photos taken by his friends, he climbed down. During the descent he placed his foot again on the hoof, damaging it. As soon as the alarm went off, however, the young man had already managed to escape with the two others," it added.

The tourist will be charged under a city penal code that prohibits the "destruction, dispersion, deterioration, disfigurement, soiling or illicit use of cultural or landscape assets."

If convicted, the tourist could be fined and banned from entering the city.

The statue was previously damaged in 2005, when someone climbed on it and broke Neptune's hand. This prompted the authorities to install CCTV cameras.

In August, German tourists were accused of spray-painting soccer graffiti on a wall of the historic Vasari Corridor nearby.

The Fountain of Neptune was commissioned in 1559 by Cosimo I de Medici, Duke of Florence, to mark the marriage of his son Francesco and the Grand Duchess Joanna of Austria.