Circumcision is a religious rite in most forms of Judaism and in Islam as well as a choice of other parents for non-religious reasons, including tradition and hygiene. In the United States, it is most frequently performed by a doctor in a hospital shortly after birth.

In his letter, Niederauer stated: "Although the issue does not concern Christians directly, as a religious leader I can only view with alarm the prospect that this misguided initiative would make it illegal for Jews and Muslims who practise their religion to live in San Francisco — for that is what the passage of such a law would mean."

Further, the archbishop wrote, "Apart from the religious aspect, the citizens of San Francisco should be outraged at the prospect of city government dictating to parents in such a sensitive matter regarding the health and hygiene of their children."

The Jewish Community Relations Council, a Bay Area organization, is spearheading opposition and has formed the Committee for Parental Choice and Religious Freedom.

An interfaith coalition that includes the Rev. Amos Brown, president of the San Francisco branch of the National Association for the Advancement of Coloured People, and Jesuit Father Stephen Privett, president of the University of San Francisco, also opposes the proposal as an infringement on religious liberty and parental rights.

Privett called the measure a "totally unnecessary and thinly disguised expression of intolerance and discrimination against centuries-old religious traditions."

The ban would not only violate religious liberty but "we should not waste citizens' time and money," the NAACP's Brown wrote in a statement.

Lloyd Schofield is the initiative's primary sponsor and part of a core committee of five working on the campaign.

"Parents don't have a right to harm their child. They can only do what is in the best interest of their child. I can guarantee a child being held down and having their genitals mutilated is not a religiously uplifting experience for the child," said Schofield.

Schofield, who details arguments for the ban on the web site sfmgm.org, said men who want to undergo the procedure removing the penis' foreskin may do so after they turn 18.

Neither parental rights nor religious freedom is more important than stopping the practice, said Schofield. He said he was raised Lutheran but practises no religion and has no children.

The Rev. James DeLange, a Lutheran pastor and chair of the San Francisco Interfaith Council, said in a statement that the ban "would turn back the clock on a right that is fundamental to the founding of (the United States) — the right to the free exercise of religion."

Abby Michelson Porth, associate director of the Jewish Community Relations Council and a leader of The Committee for Parental Choice and Religious Freedom, called the initiative an affront to religion and to religious liberty.

"Jews have performed circumcisions for 4,000 years. It is symbolic of our monotheism and our covenant with God," she said.