VATICAN CITY (AP) - Pope Francis is calling for courageous defence of children to protect them from abuse.

Francis made no mention of the church scandals in many countries in which clergy abused children and hierarchy covered up for them. At a Mass he celebrated on Sunday in crowded St Peter's Square, Francis said abuse victims are in his prayers.

He stressed that all must work with courage so that children, who are among the most vulnerable people, be always defended and protected.

Ignoring sometimes heavy rain, Francis toured the square in a popemobile, but left the vehicle to embrace disabled adults and children along his route.

In a surprise, he ventured beyond the Vatican's confines, riding the popemobile down a Rome boulevard to greet thousands of cheering faithful who couldn't fit in the square.