GENEVA — Independent human rights experts working with the United Nations have urged the Vatican to do more to stop and prevent violence and sexual abuse against children, citing “persistent allegations of obstruction and lack of cooperation” from the Catholic Church, the U.N. human rights office said.

The four experts, in a letter dated April 7 but only made public on Monday, faulted efforts by the church “to protect alleged abusers, cover up crimes, obstruct accountability of alleged abusers, and evade reparations due to victims.”

In general terms, the experts alleged bids were made by some church members to undercut efforts in national legislatures to prosecute child sex offenders, and cited lobbying attempts to limit how long former child victims can report the crimes after they become adults.

The experts said the violations had allegedly been committed over decades in many countries with tens of thousands of victims.

“We note with great concern the apparent pervasiveness of child sexual abuse cases and the apparent systematic practice of covering up and obstructing the accountability of alleged abusers belonging to the Catholic Church,” the experts said.

The four experts are working under various mandates from the U.N.-backed Human Rights Council. Though they do not work for the United Nations or speak for the world body, they do receive some administration support from the U.N human rights office.

The Vatican didn’t immediately make any public comment about the letter. It has been heavily criticized by abuse victims in many countries over failing to discipline or remove bishops or other members of the hierarchy implicated in cover-ups of allegations.