German Jesuit priest Hans Zollner talks to journalists following a press conference held by an independent commission for the study of sexual abuse of children in the Portuguese Catholic Church last month
German Jesuit priest Hans Zollner talks to journalists following a press conference held by an independent commission for the study of sexual abuse of children in the Portuguese Catholic Church last month AFP

The most influential member of a Vatican commission on tackling clerical sex abuse said Wednesday he has quit over "structural and practical issues" which made it "impossible" for him to continue.

Hans Zollner, the public face of Pope Francis's efforts to tackle the global paedophilia scandal, said he had "grown increasingly concerned" over how the papal advisory body works, "particularly in the areas of responsibility, compliance, accountability and transparency".

His resignation from the Pontifical Commission for the Protection of Minors is the latest blow to a working group dogged by controversy.

US Cardinal Sean O'Malley, the body's head, said early Wednesday that Zollner had resigned due to a heavy workload.

But German Jesuit priest and renowned academic Zollner, one of the leading experts in the fight against child abuse in the Catholic Church, said he had "noticed issues that need to be urgently addressed and which have made it impossible for me to continue further".

In a statement, he slammed "a lack of clarity" regarding the selection process of members and staff, and "inadequate" financial accountability.

"Furthermore, there should be transparency on how decisions are taken in the commission. Too often, there was insufficient information and vague communication", he said in a statement.

"It is due to these structural and practical issues that led me to disassociate myself from the Pontifical Commission for the Protection of Minors".

Zollner was the last remaining founding member of the group, which was set up by Pope Francis in 2014 as he strove to rid the Catholic Church of the scourge of sex abuse by clerics.

Problems emerged as early as 2017, when abuse survivor Marie Collins resigned as a member of the commission, saying the body was under-resourced and faced fierce resistance within high echelons of the church.

Fellow commission member and survivor Peter Saunders also quit later that year.

The pope accepted Zollner's request to step down "with the deepest of thanks for his many years of service", O'Malley said.

Francis has vowed a zero-tolerance stance on abuse and has changed the law so that suspected cases must be reported, but victims' associations say he still has not gone far enough.

Francesco Zanardi, founder of Italian survivors group Rete L'Abuso (The Abuse Network), told AFP Wednesday that Zollner had been "very honest" about the paedophile priest problem within the church "and the Vatican is making him pay".

Zollner had been increasingly sidelined over the last few years, Zanardi said.

The pope has recently tried to strengthen the commission, which was originally limited in its mandate, by making it part of the Vatican office that processes clergy sex abuse cases.

He has also tasked it with helping local churches set up survivor centres, where those who have been abused can seek help and justice.

But Zanardi said that while Zollner had been a rare contradictory voice, the commission itself was "absolutely useless".