Prince Harry and Meghan were legally married at Windsor Castle, the Archbishop of Canterbury has said.
During her interview with Oprah Winfrey, Meghan said the couple exchanged vows three days before their official wedding in May 2018.
Justin Welby said he would have been "committing a serious crime" if he had signed the marriage certificate on the actual day, knowing it was false.
But he met the couple "in a private and pastoral setting" beforehand, he said.
During a revelatory two-hour interview earlier this month, Meghan told Oprah: "You know, three days before our wedding we got married."
She said: "No-one knows that. But we called the archbishop and we just said: 'Look, this thing, this spectacle is for the world, but we want our union between us.'
"So the vows that we have framed in our room are just the two of us in our backyard with the Archbishop of Canterbury."
The archbishop was speaking to a group of European newspapers when he was asked to address Meghan's remarks.
He told Italian newspaper La Repubblica: "I met the Duke and Duchess of Sussex several times in a private and pastoral setting before the official ceremony on Saturday 19 May 2018. That day was the day of the marriage.
"If I had signed the certificate on a different day, I would have been committing a serious crime. The marriage was celebrated on the 19 May. But I won't say what occurred in our other meetings."
The Sun newspaper published a copy of Prince Harry and Meghan's wedding certificate which showed the couple were legally married at Windsor Castle.
The document was dated 19 May 2018 and showed the names of Prince Charles and Meghan's mother Doria Ragland as witnesses.