Pope Francis celebrates his birthday with extra-long pizza

Pope Francis has blown out his birthday candle on an extra-long pizza at the Vatican to the delight of children.

Francis, who turned 81 on Sunday, then told the children, who use a Vatican health service, to "eat all four meters (13 feet)" saying it will make them grow.

Pope Francis blowing out the candle at the Vatican.

Pope Francis blowing out the candle at the Vatican. (L'Osservatore Romano/Pool Photo via AP)

Later, thousands of children in St. Peter's Square shouted birthday wishes to Francis. He replied from his window overlooking the square: "Thanks a lot, thanks a lot." His birthday coincided with his weekly Sunday appearance to faithful.

Pizza for parties in Italy is often baked in long form, instead of round pies, which are meant instead for individual portions. At the Vatican, rectangular-shaped pieces of pizza were stretched end-to-end on a table and a tall, white candle stuck in the middle.