Italy's Culture Ministry has banned loans of works to the Minneapolis Institute of Art, following a dispute with the U.S. museum over an ancient marble statue believed to have been looted from Italy almost a half-century ago.

The dispute began in March 2022 when an Italian court ruled that the Minneapolis museum was irregularly in possession of the Stabiae Doriforo, a Roman-era copy of The Doryphoros of Polykleitos, an ancient Greek sculpture.

Rome claims that the sculpture was looted in the 1970s from an archaeological site at Stabiae, an ancient city close to Pompeii that was also covered by lava and ashes when Mount Vesuvius erupted in A.D. 79.

Massimo Osanna, director general of national museums for Italy's Ministry of Culture, confirmed the ban in a statement given to WCCO on Thursday.

"The situation for us is very clear: the statue was excavated illegally in Italy and illegally left our territory," Osanna said. "Until the Doryphoros will be returned, there will be no further cooperation from our entire national museum system with the museum in Minneapolis."

In February 2022, Italian prosecutors issued an international warrant for the artwork to be impounded and returned. At a news conference earlier this year, Nunzio Fragliasso, chief prosecutor at the Torre Annunziata court, said they were "still awaiting a response."

In 1984, while the work was on display in a German museum, Italy initiated a legal proceeding to claim it. The claim was denied in 1986. The U.S. museum, which bought the statue in 1986 for $2.5 million, said it was purchased from art dealer Elie Borowski and imported into the United States.

"Since that time, the work has been publicly displayed and extensively published," the Minneapolis museum said in a statement. "While it takes issue with recent press reports regarding the Doryphoros, Mia (the museum) believes that the media is not an appropriate forum to address unproven allegations."

The museum asserted that it has always acted "responsibly and proactively" with respect to claims related to its collection. However, it added, "where proof has not been provided, as well as where Mia has evidence reasonably demonstrating that a claim is not supported, Mia has declined to transfer the work."

The museum called Italy's new ban on loans "contrary to decades of exchanges between museums."

The Minnesota Institute of Art originally opened its doors in 1915. The museum expanded in 1974 and 2006. 

There are more than 89,000 objects held in the museum.