WASHINGTON — The U.S. Holocaust Museum has plunged into the fray over a controversial campaign by an animal rights group equating animals killed for meat with Holocaust victims.

In a sharply worded letter, Stuart Bender, counsel for the U.S. Holocaust Memorial Council, warned People for the Ethical Treatment of Animals (PETA) that the group is improperly using photographic reproductions from the museum in its "Holocaust on your Plate" campaign.

"We demand that you immediately and permanently cease and desist this reprehensible misuse of Holocaust materials," Bender wrote.

The campaign includes a traveling exhibition — that has been shown in San Jose and Berkeley and will soon be in Sacramento — and a Web site, which features pictures of Holocaust victims and concentration camps, juxtaposed against pictures of chickens, cows and pigs in slaughterhouses and factory farms.

In an appeal for Jewish support, the group claimed that the inspiration for the comparison came from Nobel Laureate Isaac Bashevis Singer, who was a vegetarian.

Jewish leaders were not swayed by the appeal.

Last week the Anti-Defamation League's national director, Abraham Foxman, said the campaign "takes chutzpah to new heights.

The Holocaust Council was doubly angered because it was the primary source of the Holocaust images used in the campaign. The PETA Web site offers a glimpse of the display; at the end, it said "Holocaust photos courtesy of USHMM."

But museum officials say they never gave permission for its images to be used in such a display. PETA's use of them "improperly and incorrectly implies that the museum, a federal government establishment, endorses PETA's project," the council's lawyer wrote.

On Tuesday, the animal rights group responded, insisting that use of the photographs is "consistent with the museum's mission statement," and claimed that the project is funded by an anonymous Jewish philanthropist.

The group also said it "requested, received and paid for the use of the photographs" — a claim museum officials vehemently deny.

Arthur Berger, communications director for the museum, said a representative of the group sought the materials without indicating his PETA connection or how the material would be used.

"It was clearly a misrepresentation, at minimum, of what it would be used for," he said. "There was no indication it would be used in a comparison with animals. Once we learned of this obscene connection, we sent a cease and desist letter."

Berger said the council is considering its next move and reviewing its policies for the use of photographs and other materials.