Jay-Z presents the Video Vanguard Award to his wife Beyonce as he holds their daughter Blue Ivy during the 2014 MTV Video Music Awards in California on August 24, 2014. Photo: Reuters 

US singer Beyonce has given birth to twins in Los Angeles, several celebrity news websites reported on Saturday, citing unidentified sources.

Beyonce, 35, and rapper and music producer Jay Z, already have a five-year-old daughter, Blue Ivy.

E! News, citing multiple unidentified sources, reported the birth and that Jay Z and Blue Ivy were seen at a Los Angeles area hospital on Thursday.

Us Weekly, also citing multiple unidentified sources, reported that the couple welcomed twins earlier this week.

"Bey and Jay are thrilled and have started sharing the news with their family and closest friends," one unidentified source told PEOPLE.

Reuters could not verify the reports. A representative for Beyonce did not respond immediately to a request for comment.

The celebrity news websites did not provide additional details, such as the date and time the twins were born or the *** of the infants.

The "Lemonade" singer, one of the most powerful women in the music business, announced the pregnancy on her Instagram account in February along with an image of her posed in lingerie and caressing a noticeable baby bump.

The announcement got more than 8 million "likes" in the first 24 hours to become the "most-liked" Instagram ever.

The R&B singer performed live at the Grammy awards in Los Angeles two weeks later, proudly displaying her swelling belly in a motherhood-themed show. She has since posted numerous pictures of her bare baby bump on her social media accounts.

The birth of Blue Ivy caused a paparazzi storm in 2012, with New York's Lenox Hill hospital shutting down part of its maternity wing to accommodate music's royal couple.

News of the pregnancy came less than a year after the release of Beyonce's 2016 album "Lemonade," in which she appeared to address long-standing rumours of trouble in her eight-year marriage.

The lyrics of several songs spoke about being cheated on, and regretting being married. But Beyonce made clear in the final tracks of the album and in music videos featuring Jay-Z that she had decided to stay in the relationship.

The couple have never addressed the rumours publicly.