The royal couple, both devout Catholics, had a 20-minute private audience with the pontiff. None of their four children were with them.

Mathilde, sporting an all-white outfit topped off by a lace veil, arrived for the meeting in a wheelchair but switched to crutches before being greeted by the pope.

Royal officials have not divulged how the queen injured her left leg but she is thought to have had a fall during a recent ski holiday.