Christie’s said that it cooperated with the Italian Embassy in London, as well as the owners of the objects, and that the works were returned voluntarily.
A press release on the auction house’s website stated that the works were “acquired in the past in good faith, but were more recently identified as not having the required, verifiable title, export or provenance details needed to proceed with a sale”.
The objects are understood to have been consigned by a number of different vendors and included a marble fragment from a sarcophagus in Rome's Catacombs of St Callixtus, valued at approximately £50,000.
Other works included an Etruscan terracotta mask from the 6th-5th century BC and an ancient Roman capitol.
Italian officials said the items were looted between the 1960s and 1980s but that this was "the first case of such close co-operation between Italy and a private auction house", according to Sky News.
The works were put on display in a hand-over ceremony at the Italian Embassy in London that was attended by Italian culture minister Alberto Bonisoli.
Christie’s reaffirmed that it is “fully committed to the elimination of any modern trade in illicit antiquities” and said that “it remains highly unusual for works to be withdrawn from the sale process, representing less than 0.8% of the hundreds of items offered”.
Deputy chief executive at Christie’s Stephen Brooks said: “Our primary goal today is to return these objects and to raise awareness of how vital it is to have access to all information to continue to ensure only legitimate works are offered to the market. Research and its publication is a vital part of our work.
“Our processes of due diligence make full use of current, available research and we continue to work closely with organisations, authorities and art loss databases to ensure we have verifiable title and provenance.”
Brooks thanked Raffaele Trombetta, the Italian Ambassador, for his support with this issue and said that with closer future cooperation, “we hope to ensure the required research takes place ahead of catalogue publication to continue to ensure only legitimate objects are offered in our auctions”.