Since the late 1980s, Williamson has been accused of Holocaust denial. Citing the Leuchter report, Williamson has denied that millions of Jews were murdered in Nazi concentration camps and the existence of Nazi gas chambers and praised Holocaust denier Ernst Zündel. During an interview on Swedish television recorded in November 2008, he stated: "I believe that the historical evidence is strongly against, is hugely against six million Jews having been deliberately gassed in gas chambers as a deliberate policy of Adolf Hitler", and "I think that 200,000 to 300,000 Jews perished in Nazi concentration camps, but none of them in gas chambers."