The father of pop star Beyonce turned to Twitter on June 18 to say his daughter was now the mother of twins, confirming earlier reports of the year’s most highly anticipated celebrity birth.

“They’re here!” wrote Mathew Knowles in a tweet that included a digital birthday card that read: “Happy Birthday to the twins! Love, Grandad.” The message was the first word from a family member about the birth of the twins, which is said to be on June 12.

Reuters has been unable to confirm the reports that have been circulating online about the twins’ actual date of birth.

Entertainment and gossip website TMZ said its sources reported that Beyonce gave birth to a boy and a girl on June 12 and all three remained in a Los Angeles hospital because of a “minor issue”. All three will be “okay”, the entertainment website reported on June 18.

Meanwhile, Us Weekly said that Beyonce has given birth to a twin boy and girl.

Neither Beyonce, one of the world’s most popular singers, nor her husband, the rap star and entrepreneur Jay Z, has made any announcement about the birth.

The sex of the twins is also unknown, but former US president Barack Obama hinted at the arrival of two girls in a video message broadcast at the Songwriters Hall Of Fame. They’ll join big sister Blue Ivy Carter, born in January 2012.

Beyonce announced her pregnancy via Instagram on Feb 1. The post – showing the singer embracing her baby bump in a garden scene – broke records on the social media platform. The post currently has nearly 11 million likes.

She performed at the Grammys later that month in a visual spectacle that included holographic technology. During the show, she took home trophies for Best Urban Contemporary Album (for Lemonade) and Best Music Video (for Formation). Despite having the most nominations, she got shut out in the top four categories to Adele.

Beyonce has kept a low profile in recent months, dropping out of Coachella (she was replaced by Lady Gaga) in April and skipping the New York Met Gala in May.

Representatives for the couple have not responded to requests for comment. – Reuters