VATICAN CITY: Pope Francis' efforts to show that he's tough on clerical sex abuse suffered a blow Saturday after a high-profile abuse survivor took a leave of absence from the pontiff's advisory commission.

Peter Saunders, a British advocate for survivors, had been highly critical of the slow pace of progress by the Vatican in taking measures to protect children and punish bishops who covered up for paedophile priests.

During a meeting of the commission Saturday, the Vatican said that "it was decided that Mr. Peter Saunders would take a leave of absence from his membership to consider how he might best support the commission's work."

His departure leaves just one other survivor of abuse, Marie Collins, on the commission, which was formed in 2013 to provide the Vatican with advice on protecting children, educating church personnel and parishioners about abuse, and keeping pedophiles out of the priesthood.

The commission was slow getting off the ground. But it took a big step last year when it successfully proposed that the Vatican create an in-house tribunal to hear cases of bishops accused of failing to protect their flocks.

The lack of bishop accountability has prompted years of criticism from abuse victims, advocacy groups and others that the Vatican had failed to punish or forcibly remove bishops who moved predator priests from parish to parish, where they could rape again, rather than report them to police or remove them from ministry.

The Vatican has released no information about the progress in the tribunal's work since it announced that the pope had agreed to create it.

The commission in general, and Saunders in particular, had been highly critical of Francis' decision to appoint a Chilean bishop despite allegations from abuse survivors that he had covered up for the country's most notorious paedophile. The bishop denied the charge and Francis stood by the appointment.

The commission has insisted that its mission is not to intervene in individual cases, but to craft policy guidelines for the church.