The author of a book accusing Poles of conducting a campaign against the Jews after the Holocaust could face charges of slandering the Polish nation, prosecutors said on Friday.

Jan Gross has already accused Poles of actively assisting the Nazis in persecuting Jews in World War Two. In his latest book, "Fear", he writes that anti-semitism remained prevalent in the years immediately after the Holocaust.

The book was released in Polish on Friday.

A spokesman for the Polish prosecutors' office in the southern city of Krakow said it would decide within days whether to press charges against Gross. If convicted, he could face up to three years in jail.

"The investigation was opened after numerous press publications on this matter," the spokeswoman said. "After the analysis, we will decide whether to proceed with legal action."

Gross was not immediately available for comment.

In an interview with daily Rzeczpospolita published on Friday, Gross rejected charges that his book was directed against Poland.

"I am convinced anti-semitism was one of the main poisons that were injected into the Polish identity," he was quoted as saying, and he blamed nationalist and Catholic circles.

"Will these people be finally able to say mea culpa? We'll see."

In "Fear" Gross writes that Poles often beat and killed Jews after the war, culminating in a pogrom in the southern city of Kielce, where the disappearance of an eight-year-old boy sparked a bloody reprisal against the Jewish community there.

Some Polish historians blame the pogrom on communist security forces, who they say encouraged the killing of some 40 people.