The actress became the source of intense tabloid speculation in 2008 after having an affair with married actor Balthazar Getty.

And according to Sienna, the fling was “immoral” and had serious consequences for her.

"I was really naïve, I think," she told the UK edition of Esquire magazine.

"I sabotaged things. I burnt a lot of bridges. What was going on in my private life was not an easy thing to read about. People don't want to see films with people they don't approve of in them.”

According to the star, she refused to take her career seriously and instead did whatever she felt like. Sienna admits impulsiveness cost her the career she could have had.

"I was a young 21. Not green as grass – I was by no means an innocent – but I had faith in the goodness of everyone. I was very open. And that led me into all sorts of situations that backfired,” she said. "I had no business sense whatsoever. I never read a review or paid any mind to what anyone said. It was all about the experience. And that translated to how I behaved outside work."

The Alfie star felt the best thing to do was to disappear from public life for a while, and let people forget her behaviour.

And the 32-year-old is now looking forward to having more children with actor Tom Sturridge, with whom she already shares 18-month-old daughter Marlowe.

"I feel really settled. I have a wonderful life. I'm up every morning with a little baby. That gives you incredible perspective,” she gushed.