French First Lady Carla Bruni's starring role in a Woody Allen movie is under threat, as the legendary director is having second thoughts about casting her.

Former model Bruni accepted Allen's offer of a part in a future project last year after the 'Annie Hall' filmmaker confirmed he wanted to put her in front of the camera, adding: 'I'm sure she would be wonderful... I would cast her in many different ways,' reports hollywood.com

Bruni, married to French President Nicolas Sarkozy, later excitedly confirmed she had accepted the offer: 'I don't know what the role is but I said yes... I can't miss an opportunity like this one. When I'm a grandmother I'd like to be able to say I made a film with Woody Allen.'

But Allen has doubts about his offer, and is adamant their possible partnership is 'far from certain'.

'Carla Bruni is not a woman who earns her living as an actress. She is a First Lady. She could be taken away at any moment by other duties, like a political crisis or an important event. I have to take account of the risks that there could be, and hiring her is far from certain,' he said.