Mr Irving, the right-wing historian, who believes that Hitler knew nothing of the mass extermination of European Jews and that the gas chambers at Auschwitz and Treblinka were a fiction, is to be the principal speaker at the seminar in London today.
Among those scheduled to appear are Kirk Lyons, an American lawyer who leads a neo-fascist group called Aryan Nations, and a well-known foreign speaker whose identity has been kept secret to avert a possible Home Office ban on his entry.
The Campaign against Fascism in Europe plans to picket the seminar once its location has been established.
Feelings ran high at the demonstration, which was organised by the Board of Deputies of British Jews. Protesters chanting 'never again' waved banners with slogans such as 'Irving, Stop Your Nazi Lies'.
Victor Greenberg, who was deported from Czechoslovakia to Auschwitz at the age of 15 in 1944, said: 'As someone who lost my entire family in the gas chambers, I feel that events like this seminar are an insult to the memory of those who suffered so tragically.
'My memories of Auschwitz are still all too clear. But I am concerned that a time will come when there are no eye-witnesses left and that people will start to believe the lies that are put about by the likes of David Irving.'
Arthur Tyler, who was part of a British Army unit which liberated the Bergen-Belsen camp in Germany in April 1945, said: 'To deny that all this happened is so wrong. It makes me very angry because I saw it with my own eyes.'
Mr Tyler said that his unit had thought that Belsen was merely a prison camp. 'When we entered the place, it was evening,' he said. 'We saw big mounds of things which we thought were rotting vegetables and were assailed by a peculiar sweet smell which I can still smell vividly now. In the morning, it turned out that they were piles of rotting dead bodies.'Reuse content