LOS ANGELES -- The government of Turkey is asking American museums to return dozens of artifacts that were allegedly looted from the country's archaeological sites, opening a new front in the search for antiquities smuggled out of their original countries through an illicit trade.

The J. Paul Getty Museum, the Metropolitan Museum of Art in New York City, the Cleveland Museum of Art and Harvard University's Dumbarton Oaks Research Library and Collection are among the institutions that the Turkish government has contacted, officials say.

Turkey believes the antiquities were illegally excavated and smuggled out of the country after the passage of a 1906 law that gave the state ownership of antiquities in the ground....