In order to speed up the return of the items, Turkey has threatened to stop loaning any other art to the museums, among which are the J. Paul Getty Museum, the Metropolitan Museum of Art in New York City and the Cleveland Museum of Art, the Los Angeles Times reported Friday.
"Turkey is offended because of having insincere responses to her claims," said Murat Suslu, Turkey's director general for cultural heritage and museums. "Turkey has been fighting against illicit trafficking of cultural objects since the Late Ottoman Period. Many ways were tried during the past years but they were not sufficient."
The Turkish government said it has proof some of the artifacts were excavated and traded hands in direct violation of a 1906 law that gave the country ownership of any antiquities found in the ground.
Ownership histories provided by the Getty, for instance, show 10 Turkish artifacts in its collection originated with two antiquities dealers known to have ties to illicit trade, the Times said.