A British historian charged on Wednesday that Hitler's deputy Rudolf Hess, who died in a Berlin war crimes prison after 47 years captivity, was murdered to prevent his imminent release.

Hugh Thomas said in a statement he had strong evidence contradicting the official verdict of his jailers -- World War II allies Britain, France, the Soviet Union and the United States -- that Hess, 93, hanged himself at Spandau jail last August."There is no substance in the allegation that prisoner number seven, Rudolf Hess, committed suicide . . . . On the contrary, there is overwhelming evidence that murder was committed," he said.

An inquiry carried out by British Royal Military Police concluded that Hess, the only prisoner at Spandau since 1963, had hanged himself on electrical flex tied to a window latch.

Thomas's book "Hess: A Tale of Two Murders" is to be published on Thursday.