He had pleaded guilty to the charge, based on a speech and interview he gave in Austria in 1989.

"I made a mistake when I said there were no gas chambers at Auschwitz," he told the court in the Austrian capital.

Irving appeared stunned by the sentence, and told reporters: "I'm very shocked and I'm going to appeal."

An unidentified onlooker told him: "Stay strong!"

Irving's lawyer said he considered the verdict "a little too stringent".

"I would say it's a bit of a message trial," said Elmar Kresbach.

Karen Pollock, chief executive of the UK's Holocaust Educational Trust welcomed the verdict. "Holocaust denial is anti-Semitism dressed up as intellectual debate. It should be regarded as such and treated as such," Ms Pollock told the BBC News website.

But the author and academic Deborah Lipstadt, who Irving unsuccessfully sued for libel in the UK in 2000 over claims that he was a Holocaust denier, said she was dismayed.

"I am not happy when censorship wins, and I don't believe in winning battles via censorship... The way of fighting Holocaust deniers is with history and with truth," she told the BBC News website.

Fears that the court case would provoke right-wing demonstrations and counter-protests did not materialise, the BBC's Ben Brown at the court in Vienna said.

Irving arrived in the court room handcuffed, wearing a blue suit, and carrying a copy of Hitler's War, one of many books he has written on the Nazis, and which challenges the extent of the Holocaust.

Irving was arrested in Austria in November, on a warrant dating back to 1989, when he gave a speech and interview denying the existence of gas chambers at Auschwitz.

He was stopped by police on a motorway in southern Austria, where he was visiting to give a lecture to a far-right student fraternity. He has been held in custody since then.

'I've changed'

During the one-day trial, he was questioned by the prosecutor and chief judge, and answered questions in fluent German.

He admitted that in 1989 he had denied that Nazi Germany had killed millions of Jews. He said this is what he believed, until he later saw the personal files of Adolf Eichmann, the chief organiser of the Holocaust.

"I said that then based on my knowledge at the time, but by 1991 when I came across the Eichmann papers, I wasn't saying that anymore and I wouldn't say that now," Irving told the court.

"The Nazis did murder millions of Jews."

In the past, he had claimed that Adolf Hitler knew little, if anything, about the Holocaust, and that the gas chambers were a hoax.

The judge in his 2000 libel trial declared him "an active Holocaust denier... anti-Semitic and racist".

On Monday, before the trial began, he told reporters: "I'm not a Holocaust denier. Obviously, I've changed my views.

"History is a constantly growing tree - the more you know, the more documents become available, the more you learn, and I have learned a lot since 1989."

Asked how many Jews were killed by Nazis, he replied: "I don't know the figures. I'm not an expert on the Holocaust."

Of his guilty plea, he told reporters: "I have no choice."

He said it was "ridiculous" that he was being tried for expressing an opinion.

"Of course it's a question of freedom of speech... I think within 12 months this law will have vanished from the Austrian statute book," he said.