A producer once told Zoe Saldana the only reason she was hired was to "look good in your underwear".

The actress has become a go-to choice for action heroine characters following her roles in Star Trek and Avatar in 2009, notching up parts in Guardians of the Galaxy and 2011's Colombiana, in which she plays an assassin who holds two guns while in her underwear in one scene.

While Zoe doesn't name the film in her new interview with Allure magazine, she reveals a producer told her "I hired you to look good in your underwear holding a gun" and called her a "difficult b**ch" when she tried to share her thoughts about the movie.

"I was told walking into this project that they really wanted me for the part, and that any input or ideas I had to please share them," she said. "That's what I was doing, and this producer was so bothered by the fact that he had to disrupt his vacation to call me and tell me to stop being a difficult b**ch. I thought, 'Wow, it's real. It really happens.'"

Zoe also described how she used to love being the only girl on set because it made her feel cool, but she began missing the company of women, so she was glad when her fellow female celebrities reached out to her when she became pregnant.

"I got an email from Jessica Alba - who I only know from conversations in the bathroom at events - saying, 'Hey, congratulations. This is my to-do list of how I did things. Maybe there will be something you can use,'" she explains, adding Cindy Crawford also recommended her a doctor to help sleep train her twins Cy and Bowie, who were born in November 2014.

"I get emotional because if we continue to do that, we will be unstoppable," she adds. "As opposed to nitpicking at each other for arbitrary things such as weight and hair color and purses. It's such f**king minutiae when there are bigger issues that we have to be talking about, like equal pay and equal rights."