Sienna Miller threw a superhero movie script in the trash because she found the female character's portrayal offensive.

The American Sniper actress has only been seen in supporting roles in movies, largely as the wife character, since the birth of her daughter Marlowe in 2012, and this is something she is hoping to change.

However, she has been advised that she needs to do a blockbuster or a franchise to make her a bankable star in order to get the big parts. But after reading a script for a superhero movie, the British actress was left sickened by its reading of what was supposed to have been her character.

"I was sent a superhero script that flashed back to how the character became what she was," she told the Telegraph magazine. "You saw her being a petty thief and the line was, 'She steals 20 bucks and stuffs it in her starter bra.' I was nearly sick!

"This has gone through 8,000 executives and everyone thinks it's OK to send out to women. I threw it in the bin."

Sienna also adds she doesn't want to do one just yet and will wait until the right script comes along, but she recently told Fandango she would love to play Catwoman in Ben Affleck's upcoming solo Batman movie, which he is writing and directing.

They currently star alongside each other in the upcoming Live By Night. It is the first time she has worked with Ben, but she reveals he's been supporting her career ever since first screen test with him when she landed in Los Angeles for his 2003 movie Paycheck.

"I didn't get it but he was a champion and supporter from afar, little notes here and there," she said.