The humble donkey has been a feature of the nativity in works of art and in school plays for centutries - but now its place could be under threat.

No less an authority on the subject than Pope Benedict XVI has declared the animal was not present at the birth of Christ in Bethlehem.

The pontiff made the assertion in a book he has written about the life of Jesus.

In Jesus of Nazareth - The Infancy Narratives, Pope Benedict said that no mention of animals appeared in Gospel accounts of Christ's birth.

How the beast of burden made its way into the story is tackled by the head of the Vatican. He claims it was a Hebrew invention inspired by ancient traditions from sources such as the Book of Habbakuk.

"There is no mention of animals in the Gospels," he wrote in the third instalment of his trilogy on Jesus Christ.

However, he admitted that this revision of the story was unlikely to hit stage adaptations of the nativity by children at Yuletide.

"No nativity scene will give up its ox and donkey," he said.

In the foreword Pope Benedict said: "I can at last consign to the reader the long promised little book on the narratives of Jesus's childhood. Here I have sought to interpret, in dialogue with exegetes [Biblical experts] of the past and of the present, what Matthew and Luke recount at the beginning of their Gospels about the infancy of Jesus."

He added: "I hope that this little book, notwithstanding its limits, might help many people in their path towards and with Christ."