Pope Francis yesterday baptised the child of an unmarried couple as part of a ceremony in the Sistine Chapel in Rome.

The parents, whose names have not been released, took part along with 31 other couples. The event was in commemoration of the day traditionally observing the occasion when John the Baptist baptised Jesus.

The mass took place under the famous Michelangelo fresco, in the same room as Pope Francis was elected as pontiff last year.

Pope Francis has been critical of priests who refuse to baptise children born out of wedlock, previously labelling such clergy "hypocrites".

Speaking in his trademark relaxed fashion, rather than delivering a long and formal speech, the Pope said: "You parents have the baby boy or girl to be baptised, but in a few years it will be they who will have a baby to be baptised, or a grandchild... And so goes the chain of faith.

"What does this mean? I would just tell you this: you are the ones that transmit the faith, the transmitters, you have a duty to pass on the faith to these children. It's the most beautiful legacy that you leave to them: the faith."

It is not the first time the Pope has demonstrated openness to those who have become parents outside of traditional marriage. Last September, 35-year-old retail employee Anna Romano received a call from the Argentinian Pope while on holiday. He told her he would personally baptise her child after she became pregnant with the child of a married man.

She was quoted in the Daily Mail as saying: "I addressed the letter simply to Pope Francis, the Vatican and put it in the post.

"I didn't even send it recorded delivery. I didn't really expect to get a reply but then out of the blue when I was on holiday I had a phone call from him.

"The number was from Rome, with a 06 dial code, and as soon as he started speaking I recognised the voice as his.

"I was just so surprised that he had telephoned me. He said that he had read my letter and he wanted to speak to me personally about it and reassure me that someone was worried about me."

The Telegraph quoted her as having also said: "The Pope told me I was very brave and strong to decide to keep my baby."