Pope Francis has denounced the proliferation of pornography on the internet and demanded better protections for children online.

The pontiff's remarks came as the Vatican confronts its own cross-border child porn investigation involving a top papal envoy.

Pope Francis met on Friday with participants of a Catholic Church-backed international conference on fighting child pornography and protecting children in the digital age.

He fully backed their proposals to toughen sanctions against those who abuse and exploit children online and improve technological filters to prevent young people from accessing porn online.

Pope Francis said the Catholic Church knew well the "grave error" of trying to conceal the problem of sexual abuse.

He said an international, cross-disciplinary approach was needed to protect children from the dark net and the "corruption of their minds and violence against their bodies".