Pope Francis has said that a global war on marriage is underway and Catholics must respond by helping couples stay strong and by providing pastoral care to those experiencing difficulty.

"Today there is a global war to destroy marriage," the Pope said during a meeting in Tbilisi with priests, religious, seminarians and lay people active in parish life.

"Today you do not destroy with weapons, you destroy with ideas," the Pope said. "It is ideological colonisation that destroys."

The only way to defend marriage against the onslaught, he said, is to help couples "make peace as soon as possible, before the day ends, and don't forget the three words: 'May I?' 'Thank you' and 'Forgive me.'"