Ratajczak already had been suspended from his teaching post at Opole last spring following protests over the book.

Prosecutors opened an investigation and Ratajczak went on trial for violating a new law banning the denial of Nazi and Communist-era hate crimes.

In December, a court in Opole found him guilty of spreading revisionism, but did not punish him, saying the limited distribution of the book did not prove it to be a "social threat." The court said Ratajczak had criticized the view of Holocaust revisionists in a second edition of the book.

"It was the first trial of an 'Auschwitz lie' case in Poland and the first use of the new law that makes it possible to punish for such crimes," said Stanislaw Krajewski, Poland consultant of the American Jewish Committee.

Ratajczak has consistently argued that his book did not endorse Holocaust denial but simply reported the views of Holocaust deniers.

Nonetheless, his trial became a rallying point for the extreme right in Poland.

Only 320 copies of Ratajczak's book were originally printed, and most were distributed privately. But publicity over the case led to a second edition that sold several thousand copies.

"In the second edition of the book, Ratajczak added a foreword in which he distanced himself from the revisionists," said Krajewski. "He wrote however, that while the gas chambers existed, the number of 6 million victims is very much exaggerated," he added.