WASHINGTON (AFP) - Clergy sexual abuse victims urged newly-elected Pope Francis to reform the Catholic Church and declare "zero tolerance" for sex crimes as his first official act.

"St. Francis was the greatest reformer in the history of the church, Pope Francis must do the same," the Survivors Network of Those Abused by Priests (Snap) said in a statement.

Jorge Bergoglio, the first pope from the Americas, chose his papal name in honour of St. Francis of Assisi, an Italian Catholic friar and preacher known for stressing humility.

US-based Snap warned that millions of children remain at risk from pedophile priests because the Church has not yet reversed longstanding policies of covering up reports of sexual abuse by transferring priests to unsuspecting parishes.

Insisting that the Jesuit order from which he hails has a "troubled" track record on pedophilia, Snap said that Francis "has both an enormous opportunity and duty to help prevent heinous assaults against kids by this crucial and relatively secretive segment of the Catholic clergy." "Very little about this crisis has been exposed in South and Central America. We worry about the safety of children in the church there," the group added.

"For the safety of kids and the healing of victims, we hope he starts by exposing the names of predator priests - current and former, living and deceased - in his home archdiocese." The sex abuse scandal cast its shadow over the conclave of cardinals that elected Francis after two days of votes.

Snap had called for more than a dozen cardinals to be excluded from the deliberations either for covering up abuses or for making tactless remarks about the scandals.

Vatican spokesman Federico Lombardi defended the cardinals and accused Snap and other activists of showing "negative prejudices." American Catholics, meanwhile, hailed Francis as a "man of the people" who has a reputation as an ascetic despite his archbishop's robes. He rides clattering city buses, makes his own meals and is famously accessible.