BOSTON--The National Endowment for the Arts (NEA) rejected a grant for an exhibit at the Institute for Contemporary Art, which had recently displayed photographs by Robert Mapplethorpe, prompting charges from the museum that the NEA caved in to political pressure.

"A week ago I would have said no, but now I would say that maybe there is an informal blacklist," ICA director David A. Ross said.

The institute drew protests this summer with the Mapplethorpe show. In Cincinnati, a gallery and its director were acquitted of obscenity charges after showing the same photos.

NEA chair John E. Frohnmayer told Ross yesterday that he was rejecting a $40,000 grant to fund an exhibit by Los Angeles mixed-media artist Mike Kelley. The grant had been approved by an NEA selection panel.

"It's not unusual for grants to be rejected at any level because of last-minute information or whatever," said spokesperson Virginia Falck.

Falck said NEA policy prevented the organization from saying why it rejected the grant, out of consideration of the artist's privacy.

"We get 18,000 applications a year, and we have money for only about 4000," she said.

Ross, however, cried foul.

"I see this action as an insult to the peer review system and to the artist as well as integrity of the Institute," he said. "I am both saddened and angered by it."

"We will do the show no matter what," Ross said.

Traditionally, NEA grants are recommended by a peer panel and referred to the National Council on the Arts, the agency's 26-member advisory board, but the chair has the authority to approve or deny grants on their own.

A late afternoon statement by the NEA said the council rejected the application in May, and Frohnmayer accepted the recommendation, but didn't tell the Boston museum because of a clerical error.

"Owing to an administrative over-sight, the Institute for Contemporary Arts in Boston was not notified," the NEA said. "The Art Endowment deeply regrets the error. It always is our intention to notify rejected grantees as soon as possible so that they can go on with their business."

Before the statement was issued, Ross said, "It appears that a fully political decision was made to reject this grant because the work may be considered controversial to some...It deals with any number of aspects of the dissolution of American society on a social and psychological level. [Kelley] deals with great humor and great wit and with great force and darkness as well."

Kelley's work includes pen and ink drawings, painting, film and other mediums, such as arranging stuffed animals in a room to appear as though they are having conversations.

Arthur Cohen, the ICA's marketing director, said the only piece of Kelley's art that people might consider offensive was a cartoonish drawing of a man defecating. Kelley's drawings also include depictions of disembodied sexual organs.

Ross said Kelley's work is part of several museums' permanent collections, including the Hirschhorn Museum in Washington, New York's Museum of Modern Art and the Museum of Fine Arts in Boston.

The NEA controversy began last year when Sen. Jesse Helms (R-N.C.) and other conservatives in Congress objected to NEA funding of works they considered obscene.

Helms singled out the Mapplethorpe exhibit, "The Perfect Moment," for its sexually graphic photographs and nude children.

Last week, a House compromise that would have allowed the NEA to award grants without content restrictions was derailed by the Senate Appropriations Committee, which reinstituted an anti-obscenity pledge that artists must sign before they receive grant money.

The Kelley exhibit is scheduled to be shown in Boston in October 1992 and tour other museums across the nation and in Europe.