The World Jewish Congress (WJC) has voiced outrage over a Polish town's ritual beating of a Judas effigy which looks like a caricature Orthodox Jew.
The Good Friday ritual in Pruchnik, south-eastern Poland, was filmed and posted by a Polish news website.
"Jews are deeply disturbed by this ghastly revival of medieval anti-Semitism that led to unimaginable violence and suffering," the WJC said.
More than three million Polish Jews were murdered during World War Two.
In total, Nazi Germany murdered about six million Jews in death camps in occupied Poland and killing fields in the former Soviet Union.
In the Pruchnik ritual - part of Roman Catholic Easter celebrations - children crowded round the effigy beating it with sticks, as adults dragged it through the streets. The mock Judas had a big red nose, black hat and Orthodox-style ringlets.
In the past the Catholic Church in Poland had banned such practices.
Last year a diplomatic row erupted between Israel and Poland after the conservative Polish government made it an offence to allege that the Polish nation was complicit in Nazi crimes. US officials also criticised the new law.
Later the Polish government watered down the controversial law, by scrapping the prison sentences prescribed for such offences.
Research shows that thousands of Poles collaborated with the Nazis. But many other Poles risked their lives to help Jews.