The Wiesenthal Center on Thursday urged authorities in Berlin to overturn a court ruling banning circumcision, saying it would be "a stain on today's Germany" to let it stand.
The Los Angeles-based Jewish lobby group said Chancellor Angela Merkel and German lawmakers should act immediately to reverse the June 26 ruling by a regional court in Cologne.
The German court ruling "is an attack on one of the fundamental principles of Judaism," wrote Rabbis Marvin Hier and Abraham Cooper, founder and dean and associate dean of the Center in a letter to Merkel.
"For 3,500 years, every male child has entered the Jewish people through the rite of circumcision. We are not talking about a mere custom, but a biblical principle that has defined the Jewish people from time immemorial."
They noted that Nazi dictator Adolf Hitler said "in one of his infamous anti-Semitic rants" that "conscience is a Jewish invention, it is a blemish like circumcision."
"Since the defeat of Nazism, Germany has come a long way, and worked very hard to successfully chart a new course after the horrific legacy of the Holocaust by guaranteeing religious freedom and democracy," they wrote.
"It would be a stain on today's Germany to have this ruling stand," the rabbis added.
In a decision that sparked outrage from German Jewish and Muslim groups, the German court ruled against a doctor in Cologne who had circumcised a four-year-old Muslim boy on his parents' wishes.
The judges ruled -- in what could set a legal precedent -- that the "fundamental right of the child to bodily integrity outweighed the fundamental rights of the parents."
The ruling marked a "big blow against integration," a spokesman for the Coordinating Council of Muslims in Germany, one of some 20 groups representing most of Germany's around four million Muslims, said on Wednesday.