The British historian David Irving on Monday pleaded guilty to denying the Holocaust and was sentenced to three years in prison. He conceded that he was wrong when he said there were no Nazi gas chambers at the Auschwitz death camp.

Mr. Irving, handcuffed and wearing a navy blue suit, arrived in court carrying a copy of one of his books, "Hitler's War," which challenges the extent of the Holocaust.

"I made a mistake when I said there were no gas chambers at Auschwitz," he told the court before his sentencing, at which he faced up to 10 years in prison.

"In no way did I deny the killings of millions of people by the Nazis," testified Mr. Irving, who has written nearly 30 books.

He also expressed sorrow "for all the innocent people who died during the Second World War."

Mr. Irving's lawyer, Elmar Kresbach, immediately announced that he would appeal the sentence.

"I consider the verdict a little too stringent," he said. "I would say it's a bit of a message trial."

Mr. Irving appeared shocked as the sentence was read. Moments later, an elderly man who identified himself as a family friend called out, "Stay strong, David! Stay strong!" The man was escorted from the courtroom.