US federal agents have searched four museums in California searching for antiquities stolen from south Asia.
Federal agents searched Los Angeles County Museum of Art
They suspect the items were smuggled in from Thailand and China before being given to museums, allowing the donors to claim back tax.
The scam involved smugglers putting "Made in Thailand" stickers on genuine antiques to get them through customs.
The museums are co-operating but say they had no reason to be suspicious. No arrests have been made.
Only items worth more than $5,000 (£2,500) need to be fully accounted for.
Immigration and Customs Enforcement agents searched the Los Angeles County Museum of Art (Lacma), the Bowers Museum, the Pacific Asia Museum and the Mingei International Museum.
Lacma director Michael Govan said 60 items were under suspicion.
"They came from sources who were members of the museum for many years and regular dealers, so no, there was no reason for the museum to know ahead of time."
Agents are also investigating whether Native American artefacts were illegally donated to the Bowers Museum.
All the items will remain at the museums while the investigation continues.
Mingei director Rob Sidner said: "If the results of the investigation show that these objects were improperly donated, and we were assured they were acquired properly, they will be returned to their rightful owner."