Pope Francis Photo: AFP

Pope Francis on Wednesday voiced support for same-sex couples, calling them "children of God" and saying they should be allowed to have legally recognized civil unions, in a radical shift from previous pontiffs.

The pope, whose opposition to gay marriage remains unchanged, said in filmmaker Evgeny Afineevsky's documentary Francesco, which premiered at the Rome Film Festival, "These are children of God, they have the right to a family ... What we have to create is a law of civil union, they have the right to be legally protected. I have defended that." 

According to biographer Austen Ivereigh, the future pope backed civil unions for gay couples while he was still the archbishop of Buenos Aires and known as Jorge Bergoglio.

But while Francis has previously spoken about same-sex unions, he has always voiced opposition to gay marriage, saying that marriage should only be between a man and woman.

"'Marriage is a historic word," he told French sociologist Dominique Wolton in a 2017 book of interviews.

"Always among human beings, and not only in the Church, it has been between a man and a woman. You can't just change that like that."

"Since the beginning of the pontificate the Pope has spoken of respect for homosexuals and has been against their discrimination," Vatican expert Vania de Luca told RaiNews. "The novelty today is that he defends as Pope a law for civil unions."

After becoming pope in 2013, Francis took an unprecedented welcoming tone toward LGBT individuals, launching his famous phrase, "Who am I to judge?" and welcoming gay couples to the Vatican on several occasions.