Ending their long-standing diplomatic efforts, Greek authorities have decided to launch legal action against the J. Paul Getty Museum to force the return of four antiquities they say were illegally removed from their country.

Greek Ministry of Culture officials said Tuesday that they decided to take the legal route because they were tired of waiting for the Getty to respond to their written requests for the items, which include a gold funerary wreath and two other masterpieces of the antiquities collection. Greece first asked for the items in 1996 and most recently sent a follow-up letter in May.

"It is always our principle to make every possible effort of goodwill negotiation in cases such as the one with the J.P. Getty Museum," said Petros Tatoulis, the Greek deputy minister of culture, in a statement to The Times. "In this particular case, our goodwill negotiations have not been fruitful, as our written communications to museum officials have repeatedly remained unanswered."

A senior official with the Greek police's art squad said authorities will seek assistance from Italian prosecutors, who are pressing a criminal case against former Getty antiquities curator Marion True for allegedly conspiring to traffic in looted antiquities.

The possibility of the Greek government joining with the Italians could raise the stakes for the Getty and other museums. An Italian judicial figure said the Italians had amassed evidence linking prominent antiquities dealers to Greek looters and welcomed judicial cooperation with the Greek authorities.

As part of their new legal offensive announced this week, Greek government officials have tapped a high-profile government prosecutor to investigate the Getty's acquisition of the four contested objects, three of which were purchased by True, according to the senior member of the Greek art squad.

The attorney, Ioannis Diotis, is well known for his successful prosecution of terrorists over the last 15 years. His most recent convictions included members of the November 17 extremist group, which is blamed for the killings of 23 Greek and other diplomats since the 1970s, including the CIA station chief in Athens.

In addition to the gold funerary wreath, the Greeks are asking for the return of an inscribed tombstone and a marble torso of a young woman, which they say could only have come from Greek territory. The Greeks argue that the objects, which date to about 400 BC, could only come from specific areas in the country.

They also want a fourth artifact, an archaic votive relief that J. Paul Getty bought himself in 1955. They say a scholarly journal identified it as having been stolen from an archeological site in Greece.

Any archeological object taken without government permission from that nation after it achieved independence in 1830 is considered illegally removed under Greek law.

In a statement, a Getty representative said the museum had replied to the Greek authorities' May letter last week.

"The Getty is disappointed that the Greek government has resorted to legal action when the Getty has demonstrated a willingness to consider whatever evidence the Greek government has and to discuss this matter in good faith," the statement said.

News of the Greek legal offensive comes in the midst of a growing debate over illicit antiquities in which Italian authorities have alleged that more than 100 looted artifacts have ended up at museums across the United States and in Europe and Asia.

On Tuesday, Philippe de Montebello, director of New York's Metropolitan Museum of Art, met with Italian officials in Rome for four hours to "discuss possible solutions to the problem of contested antiquities," according to a museum statement released by Met spokesman Harold Holzer.

Like most museums, the Met has said it will return antiquities when presented with "incontrovertible proof" that the items were looted or stolen from known collections.

But in the past, that standard has been nearly impossible to meet for source countries, which are often unable to prove exactly where or when artifacts were first dug up and smuggled.

The Italians have alleged that seven objects at the museum were illegally excavated and exported after a 1939 Italian law prohibited the unauthorized removal of antiquities from the country. The items include a large urn sold by True's co-defendant in the Italian case, American dealer Robert E. Hecht Jr.

Another co-defendant, Giacomo Medici, was convicted last year and is appealing a 10-year sentence.

The Italians have based their allegations on thousands of Polaroids, seized in a 1995 raid on Medici's Geneva warehouse, showing artifacts in unrestored states, presumably freshly unearthed. Investigators have traced at least 42 to the Getty, and dozens more to museums in Toledo, Cleveland, Minneapolis and Boston.