Voice actor Angelina Jolie (R) and Brad Pitt arrive for the screening of the animated film "Kung Fu Panda" by directors Mark Osborne and John Stevenson at the 61st Cannes Film Festival May 15, 2008. [Agencies]

Photographs of Angelina Jolie and Brad Pitt's newborn twins are expected to fetch 10 million.

The Hollywood couple - whose son Knox Leon and daughter Vivienne Marcheline were born in a hospital in Nice, France, on Saturday - are said to be in negotiations with various celebrity magazines for the sale of the exclusive first pictures of the babies.

Despite one magazine reportedly offering 5.5million for the shots, publicist Max Clifford thinks they could be worth even more, adding: "I think the pictures could fetch 10million, which would make it the biggest baby deal ever." Angelina's father Jon Voight - who recently reconciled with the actress after years of estrangement - has spoken of his joy following the birth of his new grandchildren.

He said: "I am deeply happy. I'm over the moon - it's magnificent. In this world, all we can hope for is that mommy and the kids are healthy. I'm very excited. If I were called today, I'd be there." Meanwhile, it has been revealed the babies' names were inspired by Angelina and Brad's heritage.

Knox was named after Brad's grandfather Hal Knox Hillhouse, and also shares the same last letter as the couple's adopted sons Maddox, six, and four-year-old Pax.

Vivienne's middle name is in honour of Angelina's late mother Marcheline Bertrand - who died last year. Linda Rosenkrantz, co-author of 'The Baby Name Bible: The Ultimate Guide By America's Baby-Naming Experts', explained: "Vivienne, the French form of Vivian, reflects her place of birth - something her parents like to do - and its meaning, 'life, alive' resonates in the uplifting way that her brother Pax's name projects an image of peace."

Brad and Angelina also have a three-year-old adopted daughter Zahara and two-year-old biological daughter Shiloh.