Pope Francis has expressed "shame and sorrow" over the latest paedophile priest scandal and vowed to "root out this tragic horror".

The Vatican said Francis was "on the side" of victims following recent revelations that 301 "predator priests" operated in the US state of Pennsylvania over the last seven decades, in many cases having their crimes covered up by the Church.

In a statement the Vatican said: "Victims should know that the pope is on their side. Those who have suffered are his priority, and the Church wants to listen to them, to root out this tragic horror that destroys the lives of the innocent.

"There are two words that can express the feelings faced with these horrible crimes: shame and sorrow."

Francis had faced mounting criticism in the United States for remaining silent for two days after the 884-page report into the Pennsylvania scandal was released on Tuesday.