An American group opposed to male circumcision has claimed to have gathered sufficient number of signatures that calls for a ban against the practice of circumcision in San Francisco as a ballot measure for November elections.

However, this early, legal experts say the move may encounter a stiff legal challenge particularly from religious groups if ever majority of the city's voters approve the proposal saying the move fringes on the constitutional rights of freedom of religion.

Jewish boys are required to undergo circumcision as part of their religious ritual. It is also a common practice amongst Muslim men which comprises the largest number of circumcised men across the world.

Fifty-nine year-old Lloyd Schofield, the leading proponent of a ban said that while circumcision is accepted in most societies, it should still be banned citing the pain it inflict on the person.

He told Reuters, "It's excruciatingly painful and permanently damaging surgery that's forced on men when they're at their weakest and most vulnerable."

Rachel Gosiengfiao, campaign services manager for the city's Department of Elections, said Schofield's group has submitted some 12,000 signatures calling for a ban. He needs only 7,200 validated signatures to qualify. Gosiengfiao said her agency would verify the petition and the signatures within 30 days.

The proposal is to make circumcision a misdemeanor crime in San Francisco if it is conducted before the boy reaches 18 regardless of the parents' religious beliefs. It also calls for a maximum penalty of one year imprisonment and a fine of $1,000.