Fresh from signing a deal to send 20 valuable antiquities across the Atlantic, the director of the Metropolitan Museum of Art last night offered a sharp criticism of Italy’s efforts to reclaim what it said was looted art.

“The whole process of how Italy prosecuted its case in the United States was shabby,” the museum chief, Philippe de Montebello, said, speaking before a packed New School auditorium at a forum on the antiquities scandal that has rocked the art world. Mr. de Montebello chastised the Italians for making their initial claims “entirely through the press,” saying that only after repeated requests by the Met did cultural officials even agree to meet with the museum.

Mr. de Montebello, who has led the Met for nearly three decades, also defended his decision to return the pieces, which included the prized Euphronios krater and a 15-piece set of Hellenistic silver. He cited “sufficiently incriminating” evidence Italian investigators had compiled in the course of their prosecutions of an Italian art dealer, Giacomo Medici, who has been convicted of trafficking in looted art.

“If you pile up enough circumstantial evidence, you’ve got something that’s beyond a reasonable doubt,” Mr. de Montebello said.

His comments came amid speculation that following Italy’s successful negotiations with the Met, Greece may be preparing claims of its own for pieces in American museums. Greek officials could not be reached for comment yesterday, and Mr. de Montebello told the New York Sun that, as of yet, Greece had made no claims against the Met.

Earlier, Mr. de Montebello told the audience that while there would be more claims for disputed pieces, “American museums have now shown that they are willing to take them seriously.” With an eye toward future claims, the Italian cultural minister, Rocco Buttiglione, has said he hoped the agreement with the Met would serve as a model. Though transferring legal title to Italy, the museum will get to keep the Euphronios on display until 2008 and the silver until 2010, at which point Italy will replace the pieces with long term loans.

Last night’s panel discussion on cultural property issues highlighted the deep tensions between museums and archaeologists over what to do with objects whose origins are not known. While museum directors and some cultural scholars have said current cultural property laws are needlessly restrictive, the Archaeological Institute of America has called for even stricter regulations on museum acquisitions and loans, saying they are necessary to protect ancient sites from looting.

Mr. de Montebello did not shy away last night, engaging in a spirited debate with another panelist, an archaeologist from the State University of New York at Stony Brook, Elizabeth Stone. He disputed Ms. Stone’s assertion that most objects with unknown provenance were looted, and challenged her to come up with a better way of dealing with a disputed piece.

“Should we condemn it into oblivion or should we bring it into the public domain?” Mr. Montebello said, echoing a point he made to reporters at a briefing last month. “If you catch the poacher of an endangered species, you put the poacher in jail, but you don’t shoot the animal. You put it in a zoo,” he said then.