Beyonce and Jay-Z have welcomed the arrival of their first child, according to reports from the US.

News broke on several celebrity websites and appears to have been confirmed on Twitter by the stars' celebrity friends, including Rihanna and Gwyneth Paltrow.

Reports suggest the baby girl, named Blue Ivy Carter, was born by Caesarean section on Saturday.

There has been no official confirmation from the couple themselves so far.

Beyonce and Jay-Z never officially announced their marriage either.

The 2008 wedding was only revealed when journalists uncovered their marriage licence, which had been filed in New York.

Many stars have taken to Twitter to pass on messages to the new parents.

Beyonce's sister Solange wrote: "The most beautiful girl in the world".

Rihanna tweeted: "Welcome to the world princess Carter! Love Aunty Rih".

Actress Gwyneth Paltrow also wrote on the social networking site: "Welcome to the world Blue! We love you already."

Hip hop mogul Russell Simmons, tweeted: "Congrats to my good friends Beyonce and Jay-Z."

Beyonce announced she was expecting her first child in August 2011 at the MTV VMAs held in Los Angeles before performing on stage.

Together since 2002, the rapper and singer married in April 2008.