LOS ANGELES, Sept 13, 2012 (AFP) - A prominent Jewish rights group expressed fears Thursday of "another blood libel" against Jews stemming from a film mocking Islam that triggered riots in Muslim countries.

The amateur film denigrating the Prophet Mohammed was promoted by evangelical and Coptic Christians living in the United States, and the 

suspected producer is a Coptic Christian living in California.

But a man claiming to be the director of the movie posed as an Israeli American Jew in interviews with US media outlets, claiming to have raised five million dollars for it from Jewish donors.

The Los Angeles-based Simon Wiesenthal Center, one of the largest international Jewish human rights organizations, said it was "deeply troubled" by those claims.

"That turns out to be a massive lie," it added. "We remain deeply worried that those initial media reports will be used by Islamist extremists to further fan the violent anti-Semitism that is a part of that sub-culture of hate."

The Wiesenthal Center, which regularly denounces anti-Semitic activities around the world as it documents the Holocaust and hunts down Nazi war criminals, urged the media to avoid casting the video as an Israeli or Jewish 

product.

"We need media to ensure that this film does not become another blood libel against world Jewry," it said.

"Blood libel" historically refers to the slander that Jews use the blood of Christian babies to make Passover matzoh, a myth used to justify pogroms and other repression.

The suspected producer of the film is Nakoula Basseley Nakoula, a 55-year-old Coptic Christian living in California. The man who claimed to be the Israeli-American director identified himself as "Sam Bacile," an apparent pseudonym.

The film was promoted on the websites of two other Americans, extremist Christian pastor Terry Jones and another Copt, Washington-based Morris Sadek.

The cast and crew have voiced anger at having been exploited for the gauche film, with at least one saying that offensive parts of dialogue had been dubbed over their own words and that they had been duped into believing they were making an adventure film set 2,000 years ago called "Desert Warrior."

Excerpts of the film posted online triggered riots at US embassies in Cairo and Yemen, along with the US consulate in the eastern Libyan city of Benghazi, where the US ambassador and three of his colleagues were killed on Tuesday.

The man who claimed to be the Israeli-American director identified himself as "Sam Bacile," an apparent pseudonym.