The leading British medical journal The Lancet has refused to disown or retract a harshly anti-Israel "open letter for the people of Gaza" that it published in August, despite some of the letter's authors being exposed as anti-Semitic activists.

The Telegraph newspaper revealed on Monday that all five of the authors "have campaigned vociferously for the Palestinian cause over many years," despite having stated in their letter that they had “no competing interests.”

Two of the five, Dr. Swee Ang, an orthopedic surgeon, and Dr. Paola Manduca, a professor of genetics at the University of Genoa in Italy, are apparently sympathetic to the views of David Duke, a white supremacist and former Ku Klux Klan Grand Wizard.

Both emailed their contacts in August endorsing a Duke video titled “CNN, Goldman Sachs & the Zio Matrix,” in which he claims that “the Zionist matrix of power controls media, politics and banking” and that “some of the Jewish elite practices racism and tribalism to advance their supremacist agenda."

“This is a shocking video please watch," Dr Ang wrote in her endorsement. "This is not about Palestine – it is about all of us!”

Dr Manduca, in a separate email, speculated that the Boston marathon bombing was perpetrated by Jews. “Let us hope that someone in the FBI is smart enough to look more carefully at the clues in Boston and find the real culprits behind these bombings instead of buying the Zionist spin,” she said.

Questioned by The Telegraph, Dr Ang said: “I didn’t know who David Duke was, or that he was connected to the Ku Klux Klan. I am concerned that if there is any truth in the video, that Jews control the media, politics and banking, what on earth is going on? I was worried.”

For her part, Dr Manduca issued a statement in which she denied being anti-Semitic. “[But] I legitimately use my right of freedom of opinion,” she said, “and do not agree or value the politics of the government of Israel, nor of many others, including Jews in and out of Israel,” she said.

The Telegraph reports that a third author of the letter, Dr Mads Gilbert, gave an interview to the Norwegian newspaper Dagbladet in 2001 in which he said that the 9/11 attacks in the United States were a result of Western foreign policy, and that he supported terror attacks in that “context.”

The Lancet refused to remove the letter from its website. “It's utterly irrelevant. It's a smear campaign,” editor Dr. Richard Horton, told The Telegraph. “I don’t honestly see what all this has to do with the Gaza letter. I have no plans to retract the letter, and I would not retract the letter even if it was found to be substantiated.”

According to the journal's critics, the Lancet’s editors have encouraged anti-Israel prejudice for many years.

“The Lancet is supposed to be a politically neutral medical journal," said Professor David Katz, an expert in infection and immunity at University College London. "The fact that they have given proven anti-Semites a platform and not rescinded it, even when confronted with the evidence, is appalling.

“They have allowed their hatred of Israel to blind them to the norms of medical science and the pursuit of reason.”

Professor Sir Mark Pepys, director of the Wolfson Drug Discovery Unit at UCL, wrote: “The failure of the Menduca et al authors to disclose their extraordinary conflicts of interest… are the most serious, unprofessional and unethical errors."

