Philippe de Montebello, director of New York's Metropolitan Museum of Art, said yesterday he is "disappointed" after reading reports that the Smithsonian Institution will receive a major collection of ancient oriental artifacts that the Met has stored since 1966. "Disappointed?" said de Montebello. "The disinherited always have that view.

"Nobody plans to do anything, but obviously the reason it was housed here was so that we would ingratiate ourselves to Dr. Arthur M. Sackler so that he might donate to us all or part of his collection."

Smithsonian Assistant Secretary Charles Blitzer would not comment yesterday on a Washington Post report that the Smithsonian was in line to receive the collection from Sackler, a wealthy New York art collector, medical publisher and psychiatrist. Sources said, however, that the institution is due to receive the collection, which would be housed at a proposed new underground oriental art museum in an open space between the Smithsonian Castle and Independence Avenue.

Though a catalogue of the collection has not been published, it is said to include valuable Chinese bronzes dating back as much as 3,000 years, and jade objects of later periods.

Both Sackler and Smithsonian Secretary S. Dillon Ripley, at last night's White House dinner for Indian Prime Minister Indira Gandhi, refused to comment on the reports. Sackler's personal attorney, Michael Sonnenreich, said "it's the Smithsonian's business" and "we're not trying to be mysterious; we just see no advantage to public discussion of these matters."

De Montebello said the decision had been "rumored for a long time.

"If the collection is in fact going to the Smithsonian, of course we're disappointed," said de Montebello. "It's without question the best privately held collection of Chinese bronzes in this country and probably the world."

Sackler, 68, is well known in the art world, having made large contributions to the Brooklyn Museum, Princeton and Harvard. He donated a sculpture by Isamu Noguchi to the National Gallery for the opening of the East Building, and the Egyptian Temple of Dendur to the Metropolitan. He was also responsible for the Metropolitan's construction of the Sackler Wing and an exhibition hall for Indian art.

Neither de Montebello nor Sonnenreich would comment directly on why Sackler apparently decided not to donate the collection--which consists of more than 5,000 pieces, including many from the Chao and Shang dynasties--to the Metropolitan.

I don't know why it's happening, that's something you'll have to ask Sackler ," said de Montebello.

Many of Sackler's oriental pieces have been stored for the past 16 years in the so-called "Sackler enclave" at the Metropolitan.

In 1978, the New York attorney general's office investigated storage arrangements at the Metropolitan, including the "Sackler enclave." "We had received information that Dr. Sackler had a space at the museum--which is a charitable organization--with a staff that was not cleared by normal museum procedures. They also had a separate phone number," said Charles Brody, the assistant attorney general who conducted the investigation. "The space was run independent of the museum and in our opinion the museum was in breach of its own practices."

After the investigation, the Metropolitan formalized the relationship with the "Sackler enclave," categorizing the collection as a loan, according to Brody.

"There was never any evidence of wrongdoing against Dr. Sackler," said Brody. "Our investigation was actually not against him but against the museum. . . . We did take a deposition from Dr. Sackler. He was not pleased to be deposed but he wasn't belligerent about it. He considered it a waste of his time. He didn't think anything was wrong and couldn't understand why we were asking him questions."

Both his personal secretary and attorney characterize Sackler as "a very private person." Asked whether the publicity surrounding the attorney general's investigation may have caused friction between Sackler and the Metropolitan, de Montebello said, "I really couldn't say anything about that.

"You are dealing with something that has to do with the mind of Dr. Sackler, so you'd have to talk to him about that since he'd be the one who may be feeling friction. . . . I can't really comment on our relationship since a relationship involves two parties.

"In all great relationships, as in all great marriages, there are moments of strain followed by moments of exaltation. It's not the end of the world if the collection goes to the Smithsonian. Sackler is a collector of enormous energy and creativity. Our relationship has been a long and good one and I'm sure it will continue."

In a similar investigation in 1974, the New York attorney general's office looked into New York's Museum of the American Indian because of the storage of Sackler's private collection of Central American art there. Sackler was cleared of any wrongdoing.

Sackler's reticence about discussing the arrangement with the Smithsonian may be explained by a rare interview he gave to The Tulsa World in 1975 in which he said he has "one of those things about the importance of privacy."

Sonnenreich would not comment on Sackler's personal wealth or business interests. "They are private," said Sonnenreich. "The only information that Dr. Sackler releases can be found in 'Who's Who.' "