"Sienna is naturally very flirty and she couldn’t keep her hands off Will. They seemed to really get on and have seen each other whenever they can, usually in Los Angeles," an insider told the paper.

"She says Will is really sweet, but she is also very focused on her career. She isn’t ready for anything as intense as her and Jude."

Although Sienna, 25, has been acting for several years, Factory Girl is only 38-year-old Will’s second studio movie. He has previously appeared in Gwyneth Paltrow flick Running With Scissors.

The secret of Sienna’s slim size - Dec 19 2006
It seems Sienna Miller has admitted to having a secret weapon in her quest to slim to tiny proportions.

The ex-fiancee of Jude Law said she had to become a size 0 to play bulimic drug addict Edie Sedgwick in new movie Factory Girl, according to the Daily Express. And her strategy? Vodka.

"I decided to drink vodka instead of wine because it has fewer calories," the 24-year-old said.

Skinny Sienna is likely to upset nutritionists with her comments as they make no mention of fruit and vegetables or regular exercise.

Female stars are often considered role models for young girls who may go to extreme lengths to look as slim as the stars.

It’s not the first time Sienna has hit the headlines for her off the cuff remarks.

She was forced to apologise to the residents of a US town earlier this year when she publicly referred to Pittsburgh - where she was filming scenes - as "sh**sburgh".

Sienna: Celebrity was never my goal - Dec 11 2006
Her on-off relationship with Jude Law made her an overnight celebrity, but Sienna Miller says that was not her goal.

"I was just never desperate to be famous, which I know sounds cliched and probably like a lie, but it is, in my case, very true," the 24-year-old actress says in the January issue of W magazine.

"And that’s the irony of my situation."

She added: "It was always about acting, and now it’s all about everything but that. I fell in love with someone very, very famous, and that’s beyond all of our control.

"Strategically I probably could have analysed it at the time and thought, ’This could potentially be very damaging’, but that was a very beautiful period of my life."

Miller, a fashion icon and Hollywood It Girl, reportedly broke off her engagement to Law last year after he publicly apologised for cheating on her following reports that he had a fling with the nanny of his three children from his marriage to fashion designer-actress Sadie Frost.

She says the 33-year-old actor remains "a very close person in my life".

"It just becomes this soap opera," she says, recalling the media attention. "And I guess I had a pretty good few episodes."

Miller stars as Andy Warhol muse Edie Sedgwick in the forthcoming movie Factory Girl.

"I know that I have a lot to prove to a certain degree, but it’s fine," said Miller, whose screen credits include roles in Layer Cake, Alfie, which starred Law, and Casanova, opposite Heath Ledger.

Jude and Sienna split again? - Nov 13 2006
Jude Law and Sienna Miller have apparently ended their turbulent on/off relationship for good.