The Italian government has relayed a formal proposal to the Metropolitan Museum of Art that would grant the museum special access to long-term loans in exchange for the return of 20 works of Greek and Roman art that the Italians say were illegally removed from their country. The proposed accord, a copy of which was provided to The New York Times, would specifically absolve the museum of any knowledge of wrongdoing and avert possible legal steps against the museum by the Italian government. Over the past few months, Italy has pursued a campaign against American museums to recover stolen antiquities. It includes a criminal trial in Rome of Marion True, formerly a curator at the J. Paul Getty Museum in Los Angeles. A co-defendant in that case is Robert Hecht, an art dealer who has sold numerous works to the Met over the years, including a fifth-century B.C. vase painted by the Greek artist Euphronios, which Italian officials maintain was stolen from an Etruscan tomb in Cerveteri. At the heart of the proposal is an arrangement that would allow Italy to retrieve the fifth-century B.C. vase and a set of 15 pieces of Hellenistic silver. Both the vase and the silver would remain on loan to the museum through the end of 2007 with a label identifying them as belonging to the Italian state, the proposed pact says. The objects would then go back to Italy in exchange for a series of four-year loans of an alternative work or group of works "of similar value," according to the Italian-language document provided to The Times. In the case of the silver, the proposal also calls for the objects to be made available again to the museum in 2012 for a four-year loan. Maurizio Fiorilli, a lawyer for the Italian Culture Ministry, said the proposed pact was sent to New York this week through a courier service. Harold Holzer, a spokesman for the Met, said that the museum has not yet received the proposal and that it would not comment until the museum had "received and reviewed" the documents. But a written summary of recent talks between the two sides, also provided to The Times, indicates that the proposal is closely based on a concept that Philippe de Montebello, the museum's director, discussed with Italian officials in November. The proposal also calls for the unconditional return of four terra cotta vessels, among them a wine jug, decorated with horsemen, and an Apulian mixing bowl depicting scenes of Greek mythology in the red-figure style. The forfeiture of these items, which were cited in a 2004 case against an Italian art dealer convicted of antiquities smuggling, does not include a provision for special loans. It is not clear how the museum might respond to the proposal. At the meeting on Nov. 22 with Italian cultural officials, Mr. de Montebello outlined a similar restitution-for-loans approach, according to Mr. Holzer and Italian officials. After the meeting, Mr. de Montebello also said that if Italy can provide "incontrovertible proof" that the objects are of illicit origin, the museum would consider returning those works in exchange for access to objects of "equal importance and beauty." Mr. de Montebello has also said that any restitution proposal by the Italian government would be subject to review and approval by the museum's trustees. The trustees last met on Tuesday, when the proposal had not yet been received, and the next scheduled meeting of the full board is to take place in March. Cultural Ministry officials say they expect an answer from the museum by February and that they may consider further legal investigation of the museum's acquisitions, if the Met does not respond. Under Italian law, any ancient artwork unearthed from Italian soil since 1939 belongs to the Italian government and cannot be exported without a permit. As a result, Italy has laid claim to numerous works acquired by the Met and other American museums. Italy contends that many of these works were dug up by looters who worked for international art dealers with ties to top museums. For several of the objects at the Met, including the Euphronios cup, Italian officials say they have strong evidence from a variety of sources demonstrating that the works were illegally removed from Italy. Italian officials say they have sent the Met a summary of such evidence, including photographs indicating that the artifacts were clandestinely excavated, and documents linked to dealers accused of trading in illegal antiquities. But Italian officials acknowledge that it is unclear how such evidence would stand up in any court. Today, hearings in the case against Ms. True and Mr. Hecht resume in Rome. Elisabetta Povoledo contributed reporting from Rome for this article. Correction: Jan. 16, 2006 A picture caption on Friday with an article about an Italian proposal for an accord under which the Metropolitan Museum of Art would return some antiquities to Italy misidentified a piece of silver and the century in which it was made. It is a medallion, not a plate; it is thought to date from the third century B.C., not the fifth century B.C.