The National Institutes of Health, which has had custody of 15 monkeys since they were seized five years ago from a Silver Spring laboratory amid charges of animal cruelty, said yesterday it is willing to transfer them to a primate research center "where they can live out their natural lives."

NIH said in a statement that the monkeys, once used in research on spinal cord injuries, would not undergo further "invasive procedures for research." Instead, officials said, efforts would be made to "resocialize" them after years of confinement in separate laboratory cages.

NIH has said in the past that it could not transfer the monkeys because it is not the legal owner.

Animal rights activist Alex Pacheco, whose complaints concerning the monkeys led to the raid on the laboratory in 1981, said the announcement was a major step but said the statement was "an attempt to save face . . . a backhanded way of saying the experiment is not worth finishing."

Pacheco and members of People for the Ethical Treatment of Animals have been demonstrating outside NIH since April in an attempt to pressure NIH Director James B. Wyngaarden into sending the monkeys to a private sanctuary in Texas. Pacheco complained last night that the NIH plan would force the monkeys to spend the rest of their lives in a laboratory instead of a primate sanctuary.

"There's no scientific reason" to leave them in a laboratory, Pacheco said, "no economic reason, and no ethical reason."

The animals were confiscated in September 1981, when Montgomery County police raided the Institute of Behavioral Resources Inc., the Silver Spring laboratory of an NIH-funded researcher.

Wyngaarden said yesterday that the knowledge gained from trying to resocialize and breed the monkeys could help provide a better understanding of primate behavior in group situations. Upon the natural death of each animal, he said, autopsies would be performed, with special attention in cases where the spinal cord has been surgically altered.

"This plan recognizes the concerns of the Congress and the public and guarantees the future well-being of these research primates," Wyngaarden said.