Sienna Miller has thanked Ben Affleck for being a "vocal supporter" of her as an actress.

Sienna Miller

Sienna Miller

The 35-year-old British beauty was cast by Affleck in his new gangster movie 'Live by Night' - which he has written, directed and stars in - and she is grateful to him for always championing her acting talents, even at times she was unfairly criticised.

Sienna - who plays Emma Gould, the mistress of notorious criminal Albert White (Robert Glenister), in the film - said: "Funnily enough, the first ever screen test I did was with Ben and I loved him from that moment. He's always been a vocal supporter of mine as an actor and felt like I hadn't had the opportunities I deserved."

In recent years Sienna has starred in the Oscar-winning film 'American Sniper' and the Academy Award nominated 'Foxcatcher' and received a Golden Globe nomination herself for her performance in 2012 film 'The Girl'.

The actress has stated before that she believes her tempestuous romance with Jude Law was responsible for diminishing her credibility as a thespian, but in recent years she can see the tide of opinion has turned.

Speaking to HELLO! magazine, she said: "I think I get a little more respect. My whole life I've battled perceptions of, 'Oh, she's got to be just some dumb, frivolous party girl.' But I've always been a bit more studious and deep than the perception. I felt like people didn't look at that or want to take me seriously because I was fashionable or had a famous boyfriend ... I was constantly battling to say I was a serious person and then I went and had a baby and turned 30 and people were like, 'Ooh, she's an actor.' But I was always an actor ... When you turn 30 the really great roles start to pop up and you have to relinquish vanity and focus on not being as recognisable on screen."