The accusations made Wednesday by Deputy Mayor Joseph Lhota and the city's top lawyer, Michael Hess, came a day after the museum sued to stop Mayor Rudolph Giuliani from freezing its funding over the dispute.
Giuliani has threatened to cut $7 million in city funding to the museum, or about one-third of the museum's budget.
On Thursday, a protective Plexiglas shield was placed in front of the dung-stained portrait of the Virgin Mary at the center of the controversy, museum director Arnold Lehman said.
"We are concerned for the safety of that work because of the incredibly high level of rhetoric surrounding it," Lehman said of the piece by British artist Chris Ofili that has offended Roman Catholics, including the mayor.
Also Thursday, self-proclaimed artist Scott LoBaido was grabbed by police for throwing horse manure at the museum. He said the excrement embodied his First Amendment right to protest the upcoming exhibit.
Police disagreed, taking him away after less than five minutes.
The controversial pieces are from advertising executive Charles Saatchi's collection. Lhota and Hess say the museum planned the Sensation exhibition, working behind the scenes with Christie's auction house, so the works would fetch high prices at auction once the show closes. Christie's is helping sponsor the exhibit.
The museum's board members are "shilling for a British subject who is a multimillionaire and trying to enhance his art collection,'' Lhota said.
He cited a New York Observer article which said that after the show closed in London, Saatchi auctioned 128 pieces from his collection, many of them by artists in the show.
Giuliani, on a fund-raising trip in California, said he has been in touch with Lhota and Hess about their accusations. He said the project raises the question whether a publicly funded museum should engage in "shock commercialization.''
Frederick Goetzen, spokesman for Christie's in London, said today that in December 1998, "We sold 130 works from the Saatchi collection to create bursaries (scholarships) for young artists.'' He said none of the works sold were in the Sensation exhibit, but a number of them were by artists featured in the show.
But Andree Corroon, a spokeswoman for Christie's in New York, said the house had no plans for an auction afterward.
"This bewildering accusation has absolutely no substance, is absolutely not true,'' she said.
In a statement, the museum called the accusations "preposterous and misleading.'' The show opens Saturday.
Meanwhile, a federal judge has been asked to decide whether to restore the museum's funding. The museum sued the city on Tuesday, saying Giuliani's act violates the First Amendment.
The leaders of two doen cultural institutions, including the Metropolitan Museum and the Museum of Modern Art, signed a letter protesting the mayor's funding cut.
In Washington, the Senate agreed unanimously Wednesday to a non-binding measure calling for the withholding of federal funds from the museum unless it cancels the exhibit. Independent Sen. Bob Smith of New Hampshire said the museum has received $500,000 from the National Endowment for the Arts in the last three years.