Actors Brad Pitt, left, and Angelina Jolie, here in mid-May at the Cannes Film Festival, already have four children. (Matt Sayles/Associated Press)

The Brangelina twins are here: Angelina Jolie, with partner Brad Pitt by her side, has given birth to a girl and a boy.

The obstetrician who delivered the twins, Dr. Michel Sussmann, told the Associated Press that the actress, the babies and Jolie's partner "are doing marvellously well."

Sussmann said Jolie gave birth to a boy, Knox Leon, and a girl, Vivienne Marcheline, by caesarean section on Saturday night.

He said on Sunday morning that the boy weighed 5.03 pounds and the girl was five pounds. The 33-year-old actress gave birth at around 8 p.m on Saturday night, said the doctor.

Pitt was there during the operation, said the doctor, who delivered the twins at the seaside Lenval hospital in Nice in southern France.

"Everything is going well," said Sussmann. "The mother, the babies, the father are doing marvellously well."

He said the caesarean was moved forward from its originally planned date "for medical reasons," so that the babies could be born "in the best conditions." Sussmann did not give details.

He said Jolie is expected to stay in the hospital for a few more days. The doctor said he believed the baby girl's middle name was chosen in honour of Jolie's mother, actress Marcheline Bertrand, who died in January 2007 after a 7½-year battle with cancer.

Jolie and Pitt already have four children: Maddox, 6, Pax, 4, Zahara, 3, and Shiloh, 2.

Arrived by helicopter

The actress had checked into the hospital late last month to rest and be monitored by her doctor before the birth.

Before that, she, Pitt and their children had moved into a large estate, Miraval, in the French hamlet of Correns, which is just a short helicopter ride from the hospital. Correns is about 96.5 kilometres from Nice, a resort on the Mediterranean.

Though the lenses of the world's paparazzi had been trained on maternity wards across the French Riviera, Jolie managed to slip unobserved into the clinic, which has magnificent views of the Mediterranean, reportedly arriving by helicopter on the hospital's rooftop helipad.

Pitt was seen coming and going after Jolie's hospitalization became public.

The first photos of the new twins are expected to fetch millions of dollars.

Room windows coated so no photos

Paparazzi gathered outside the hospital in Nice on Sunday morning, hoping for a shot of Pitt.

Local newspaper Nice Matin, which first broke news of the birth, reported Sunday that the couple have sold rights for the first photo of their newly enlarged family to a U.S. publication, which it did not name, and that the proceeds would go to charity.

The newspaper gave no source for that information. But the doctor told AP the couple decided to announce the birth to Nice Matin first because of its links to Nice. The newspaper called the twins "the most famous babies in the world."

Earlier this week, the hospital said it had coated the windows of Jolie's room with a special material to prevent paparazzi from taking unauthorized pictures of the star couple.

The hospital said photos in magazines and on the Internet which purported to show Jolie and Pitt in their room were fake, either manipulated or showing other patients at the hospital.

Tourists and residents of Nice, a popular resort, welcomed news of the birth. The city's mayor, Christian Estrosi, had previously told The AP that the twins will always be considered honourary citizens of the city, regardless of whether they opt to obtain French citizenship.

Estrosi said it was a "very great honour" for Nice that the Hollywood couple chose to give birth there.