Pop superstar Enrique Iglesias has broken his silence about becoming a first-time father after debuting one of his newborn twins on social media.

The Hero hitmaker and his longtime girlfriend Anna Kournikova hit headlines in December (17) amid reports suggesting they had secretly welcomed twins - a son named Nicholas and a daughter called Lucy - in Miami, Florida.

The famously-private couple didn't comment on the news at the time, but as the babies turned one month old this week, Enrique took to Instagram to share his joy at fatherhood.

"My Sunshine," the proud dad captioned a photo of himself snuggling with his sleeping child, whose identity has not been revealed. The tot sported a grey and white striped onesie as Enrique, wearing a grey hooded sweatshirt, lay his head beside the baby and gazed at his little one.

Former tennis star Anna has since also posted a picture of her own, holding up one of the babies, dressed in an all-grey onesie, as she plants a big kiss on the child's cheek. She used the same caption, and also failed to indicate if she was showing off Nicholas or Lucy.

The snaps give fans a rare glimpse into the couple's private life.

Anna and Enrique, who have been dating since 2001, managed to keep her entire pregnancy under wraps until days after she gave birth, but fans have become used to the couple's penchant for secrecy, as the sportswoman and the singer are rarely spotted out in public together and hardly ever comment on rumours surrounding their relationship.

Last year (17), Iglesias revealed his own dad, fellow singing superstar Julio, had yet to meet his girlfriend.

"They have to meet at some point," he said, according to The Sun newspaper, adding that Anna and his father are rarely in the same country at the same time.