The United States has returned more than 250 ancient artefacts to Italy after police discovered that they had been stolen.

The art unit of Italy’s police force found the items had been looted and sold to US museums and private collectors in the 1990s.

Among the precious artefacts include pots, paintings and sculptures – some up to 3,000 years old.

Several of the mosaics are worth tens of millions of euros.

The oldest item dates back to the Villanovan age (1000 – 750BC), while other artefacts were from the Etruscan civilisation (800 – 200BC), Magna Graecia (750 – 400BC) and Imperial Rome (27BC – 476AD).

Most artefacts had been stolen in the 1990s, then sold through a series of dealers with one selection apparently being offered to the Menil Collection, a museum in Houston, Texas.

The Italian Culture of Ministry said the artefacts were on display in the Menil Collection, but a spokesperson for the museum denied this and said they had never been a part of the collection.

The spokesperson said the museum had been offered the artefacts as a gift, but instead referred the donor to Italy’s culture ministry.

The ministry said the owner of the collection “spontaneously” returned the items after police found that they had come from illegal excavations of archaeological sites.

Separately, the ministry said that 145 of the returned artefacts had come from a bankruptcy procedure against an English antiques dealer, Robin Symes, who amassed thousands of pieces as part of a network of illegal traders.

Italy has long sought to track down antiques and artefacts that have been stolen and sold to private collectors and museums.

In September 2022, New York returned $19m (£16m) worth of stolen art to Italy, including a marble head of the goddess Athena dated 200BC, worth an estimated $3m alone.