Sixty years ago, on July 4, 1946, the worst anti-Jewish pogrom in the post-war history of East Central Europe took place in the Polish city of Kielce.

Forty-two members of the local Jewish community were murdered and more than 100 injured. The slaughter lasted more than six hours and was evidently carried out in a climate of enthusiastic festivity by ordinary Polish civilians, along with soldiers and militiamen.

To this day, the causes of the pogrom are a matter of controversy. There are those who maintain that it was instigated by Soviet security forces to divert attention from the rigging of a referendum held five days before by the Polish communist government in order to reinforce its hold on power. The communists certainly used the pogrom to discredit their political opponents and all those "reactionary" elements whom they accused of sabotaging "the rebuilding of Poland."

A more likely explanation emphasizes the pogrom's spontaneous character against the background of extreme nationalism, a civil war situation in Poland, resentment at the new communist regime, the persistent myth of the Jews as an "enemy of the Polish nation" and the effects of Hitler's wartime propaganda.

The pogrom followed a series of violent anti-Semitic incidents in the Kielce region and elsewhere in Poland after 1945, which claimed about 2,000 Jewish victims. The local violence was directed at former Jewish residents of Kielce who had survived the camps or hidden in the forests until the liberation of Poland from Nazi rule; it occurred at a time of intense anti-Semitic hatred, when rumors were rampant that masses of Jews would soon return to Poland from the USSR to reclaim their houses and belongings.

The more immediate cause was the ritual murder myth, which had been widely disseminated by the Catholic Church in between-the-wars Poland and was still believed by many lower-class Poles.

Rumors had begun to spread in June 1946 that Jews on Planty Avenue in Kielce were killing Polish children and drinking their blood or using it to make matzot. One Jewish eyewitness who survived the pogrom remembered: "At about nine o'clock, on 4 July, crowds started to surround the building. I heard voices from the crowd: 'You Jews have killed 14 of our children! Mothers and fathers unite to kill all the Jews!'"

Many years later,, shortly after the fall of communism in Poland, I visited the building at 7 Planty Street where the massacre took place. Anti-Semitism was still rife at that time in a general atmosphere of insecurity and political conflict, despite the fact that there were barely 10,000 Jews left in Poland.

KIELCE MARKED an ignominious low point in the millennial history of Polish Jewry - one which had a traumatic effect on the remnant that had survived the German mass murders. My parents, who returned to Poland from the Soviet Union only three weeks before the Kielce massacre, resolved like many other Polish Jews to abandon their homeland in the aftermath of this event.

Today, anti-Semitism is once more on the rise in Poland. A far-right Catholic party known for its anti-Jewish positions is in the coalition government and its leader, Roman Giertych, is minister of education. The staunchly Catholic Radio Maryja, which has several million listeners and periodically broadcasts anti-Semitic propaganda, is another disturbing symptom of the current climate in Poland.

Moreover, only last month, Poland's Chief Rabbi Michael Schuldrich was insulted and sprayed with tear gas on a street in Warsaw just before the pope's visit to Auschwitz-Birkenau. But contemporary Polish anti-Semitism is less violent than in France and Germany. Moreover, it is vigorously opposed by the authorities and treated as a serious crime by the police.

Despite the racism that still exists in Poland, there is nothing remotely comparable to the savage anti-Semitism that prevailed in Kielce six decades ago. Nevertheless, the seeds of intolerance are clearly present and require a firm response to prevent any relapse into the horrors of the past.

The writer is head of the Vidal Sassoon International Center for the Study of Anti-Semitism at the Hebrew University of Jerusalem. His latest book, in Hebrew, is Laboratory for World Destruction: Germans and Jews in Central Europe.