VATICAN CITY • An image of Pope Francis slapping his way free from the clutches of an admirer late on Tuesday had social media abuzz, with comments on the pontiff's prompt riposte.

Pope Francis had greeted children before the Nativity scene on St Peter's Square and was turning away when the woman cried out something, grabbed his hand and almost caused him to fall.

The 83-year-old head of the Catholic Church grimaced before managing to break free by slapping the woman's hand twice.

He then continued his tour, walking with some difficulty while maintaining a slightly greater distance from visitors, and gradually relaxed again as he came into contact with other children.

The woman had made the sign of the cross as the Pope approached. It was not clear what she was saying as she subsequently tugged him towards her.

Comments on Twitter were mostly supportive of the pontiff's instinctive reaction. "He is human... (Being) a Pope doesn't make you immune to pain or avoid reaction to pain," one typical comment read.

In his first mass of the new year, the pontiff yesterday nonetheless denounced all violence against women as "a profanation of God, born of a woman", a position underscored by several Twitter enthusiasts.

A personal apology followed. "We lose patience many times," Pope Francis confessed. "It happens to me too. I apologise for the bad example given yesterday," he said before celebrating mass at the Vatican.

AGENCE FRANCE-PRESSE, REUTERS