Dustin Hoffman names the day after Angelina Jolie confirms 'I AM expecting twins'

The glamorous mum-to-be wore an flowing Thomas Wylde dress for the premiere of her new animated film, Kung Fu Panda, in which she provides the voice of Master Tigress.

The news about the couple's double baby-joy was accidentally broken today by Jack Black, who also appears in the film.

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Black let slip the actress was expecting twins and fellow co-star Dustin Hoffman put his foot in it by announcing the date their co-star is due to give birth – August 19.

Ironically, both Black and Hoffman let slip the secret details to the same reporter, Natalie Morales of The Today Show.

It appears that even Hollywood is excited about Brad and Angie's baby news.

Reporter Morales, who surely couldn't believe her luck said: "It seems like everybody is bursting at the seams around her with her baby news".

Veteran Hoffman has starred with Jolie's dad, Jon Voight, in his breakthrough movie 'Midnight Cowboy' (1969).

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At a press conference today about the film, asked about reports she was planning to give birth in France, she replied that she had not completely decided, but added: "We are certainly thinking of France."

She said French was a second language which her children were starting to speak "so being here is very good for them at this time".

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At the photocall Black looked somewhat sheepish, as well he should, as it was his slip of the tongue that forced Angelina to confirm reports that she and Pitt were expecting twins, on the opening day of the annual film festival.

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Yesterday Jack and Angelina were having a joint interview to promote their film at the festival when the actor said to her: "You're gonna have as many as (the) Brady Bunch when you have these."

Asked if she was expecting twins, Angelina replied, "Yeah, yeah, we've confirmed that already. Well, Jack's just confirmed it actually."

"Is that true?", Black said jokingly, to which Jolie laughingly replied, "Yeah, you did".

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But the star stopped short of revealing the gender of what will be her fifth and six children, and said: "We would like to keep that private".

The 32-year-old arrived alone for the interview at the Carlton Palace hotel with U.S. 'Today' show host Natalie Morales.

There was no sign of partner Brad Pitt who had earlier been seen driving her around the French Riviera. The family are currently staying at Microsoft co-founder Paul Allen's Villa Maryland in St Jean Cap Ferrat in the south of France while in town for the festival.

And have been enjoying quality time with their children in between work duties.

The couple are said to have chosen France for the location of the birth of their twins, in tribute to Angelina's French-Canadian mother Marcheline Bertrand who died last year.

Angelina is keen to embrace her French roots, and the couple are reported to have bought a chateau in the south of France, and Maddox is enrolled at a French school in the US.

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The news that Angelina is expecting twins will take their brood to a burgeoning six members.

They already have a biological daughter Shiloh, 23 months, and children Maddox, seven, Pax, four, and Zahara, three.

Angelina's latest film, Changeling - a 1920s thriller directed by Clint Eastwood - is in the running for the coveted Palme d'Or award at Cannes.

Stars including Julianne Moore, Cate Blanchett and Eva Longoria dressed up to attend the film's premiere at Cannes last night.

But despite their best efforts on the red carpet, it was Angelina who stole the limelight with her baby news.

Cynics have even suggested that the indiscretions were particularly timely, guaranteeing Angelina maximum exposure as she promotes two films at the notoriously competitive festival.

But it seems the pregnancy is taking its toll.

The actress wore Nike insoles in her shoes and said the Christian Louboutin heels were lowered especially.