Dame Helen Mirren has encouraged actresses to seek out roles written for men.
The Queen star plays an army colonel in her new drone drama Eye In The Sky, a part that was originally written for a male actor.
The Oscar winner said she was "cross" that so many men hoovered up film roles, regardless of their place on the call sheet.
She told the BBC: "You look at a scene and it's going to be all men around a table and you think at least half of those could have been women.
"It's so hard to get a job as an actress, let alone as a star but just a job - to be a working actress it's so much more difficult than it is for men."
Dame Helen's colonel, who is trying to get a drone strike in Nairobi authorised, was originally written as a man but was changed to a woman before it was offered to her.
She says the move opened up a debate about the issues of the film amongst audiences, adding: "The film is about the discussions people have when they leave the cinema and having a woman in that role allows you to make that discussion.
"As opposed to saying 'well that's men, that's what men do in war'."
Dame Helen said the lack of female roles even extended as far as extras, adding: "The only time that there is more women on the set as extras is a swimming pool scene and they're all in bikinis - any swimming pool scene and suddenly it's full of women."
Sandra Bullock has previously revealed that her role as a political campaign manager in Our Brand Is Crisis was written for a man until she lobbied producers George Clooney and Grant Heslov to give her the part.
She said she got her agent to find scripts with interesting male roles and then pursued them for herself.