Hollywood star Angelina Jolie has given birth to healthy twins, a girl and a boy, in the French Riviera maternity clinic she has checked into, the Nice-Matin newspaper has reported, quoting her gynaecologist.

The twins, Knox Leon and Vivienne Marcheline, were born shortly before 8pm on Saturday (0300 AEST Sunday), the paper said quoting gynaecologist Michel Sussmann.

Jolie is fine after having a Caesarian section, it added.

Knox Leon was reported to weigh 2.27 kilograms (five pounds) and Vivienne Marcheline 2.28 kilograms (5.02 pounds).

The babies' first photograph was sold to a US paper for $US11 million ($A11.45 million), Nice-Matin said, adding that the money would be given to a humanitarian cause.

A source close to the clinic had said earlier the birth was expected in mid-August.

The twins brought 33-year-old Jolie's brood with partner Brad Pitt to six.

Pitt was seen entering Nice's Santa Maria clinic, part of the Lanval hospital on the seafront Promenade des Anglais, on July 2 with at least two of their children.

A spokesperson for Lanval could not immediately be reached Sunday morning to confirm the report.

Jolie and Pitt, 44, have been the subject of celebrity gossip fascination since they met on the set of their 2005 film Mr and Mrs Smith.

Dubbed "Brangelina," they have adopted three children: Maddox, six, born in Cambodia; four-year-old Pax, born in Vietnam; and Zahara, three, born in Ethiopia.

They also had a biological child, Shiloh, born in Namibia, in May 2006.

The pair, who frequently top magazine lists of the world's most beautiful people or couple, set up home in May in a chateau they rented from an American acquaintance in France's Provence region.

Pitt was previously married to Friends star Jennifer Aniston, while Jolie has been married twice before.