The high court heard lecturer and author Ralph Schoenman, a friend of Russell who worked with him between 1961 and 1968, had been accused of being "an appalingly sinister figure" in a philosophy primer, Confessions of a Philosopher, written by Bryan Magee.

Schoenman sued the author, Orion Publishing Group and Orion Books over passages in the book and accepted damages believed to amount to £100,000, an apology, and an undertaking that existing copies of the book would be pulped.

The court was told the book had claimed that many people believed Schoenman had been "planted on Bertrand Russell by the CIA with the mission of discrediting him internationally and that is what occurred as a direct result of his handling of Bertrand Russell".

Mr Justice Morland also heard that Magee described Schoenman, who now lives in San Francisco, as: "An appallingly sinsister figure, like an evil dwarf out of Wagner's Ring, and his motivations were unquestionably calculated and manipulative."

But yesterday Roy Furness, representing Magee and the Orion companies, who are also to foot Schoenman's legal costs, said it was accepted that the allegations were not true and that they regretted and apologised for the fact they were ever published.

Schoenman's solicitor, Liz Hartley, said the allegations "could not have been more damaging". She added: "This wholly unmerited and malicious description of the claimant, which should never have been published, is unreservedly withdrawn."