THE Vatican has come under blistering criticism from a United Nations committee for its handling of the global priest sex abuse scandal, facing its most intense public grilling ever over allegations it protected paedophile priests at the expense of victims.

Monsignor Charles Scicluna, the Vatican's former sex crimes prosecutor, acknowledged the Holy See had been slow to face the crisis but said it was now committed to doing so. He encouraged prosecutors to take action against anyone who obstructs justice, which could mean bishops who moved priests from diocese to diocese should be held accountable.

Monsignor Scicluna told the committee: "The Holy See gets it. Let's not say too late or not. But there are certain things that need to be done differently."

He was responding to questioning by the UN committee over the Holy See's failure to abide by terms of a treaty calling all appropriate measures to keep children safe. Critics allege the church enabled the rape of thousands of children by protecting paedophile priests to defend its reputation.

The committee's main human rights investigator, Sara Oviedo, was particularly tough, pressing the Vatican on the frequent ways abusive priests were transferred rather than turned in to police. Given the church's "zero tolerance" policy, she asked, why were there "efforts to cover up and obscure these types of cases?"

Another committee member, Maria Rita Parsi, an Italian psychologist and psychotherapist, pressed further: "If these events continue to be hidden and covered up, to what extent will children be affected?"

The Holy See ratified the convention in 1990 and submitted a first implementation report in 1994. But it did not provide progress reports for nearly two decades. It only submitted one in 2012 after coming under criticism following the 2010 explosion of child sex abuse cases in Europe and beyond.

Victims' groups and human rights organisations teamed up to press the UN committee to challenge the Holy See on its abuse record, providing written testimony from victims and evidence outlining the global scale of the problem.

Their reports cite case studies in Mexico and the UK, grand jury investigations in America, and government fact-finding inquiries from Canada to Ireland to Australia that detail how the Vatican's policies, its culture of secrecy and fear of scandal contributed to the problem.

The Holy See has long insisted it was not responsible for the crimes of priests committed around the world, saying priests are not employees of the Vatican but are rather citizens of countries where they live and subject to local law enforcement.

It has maintained bishops were responsible for the priests in their care, not the Pope.

But victims' groups and human rights organisations provided the committee with the Vatican's own documentation showing how it discouraged bishops from reporting abusers to police.

Committee member Jorge Cardona Llorens, a Spanish international law professor, demanded to know how the Vatican would create "specific criteria" for putting children's interests first.

Monsignor Scicluna said the Holy See wanted to be a model for how to protect children and care for victims.