The comedienne produces and stars in the film, a dark comedy about a TV reporter who sets off to Afghanistan to try her hand at war reporting.

Tina optioned the project, based on journalist Kim Barker's memoir The Taliban Shuffle, after reading a review of the book in the New York Times, and she reveals she had requested casting directors seek out native speakers for key roles.

However, they pushed to have Martha Marcy May Marlene star Christopher portray Baker's Afghan fixer Fahim Ahmadzai - and the decision hasn't gone down well with diversity critics.

Many film fans took to social media to blast the move, while they also expressed concern that another Caucasian actor, British veteran Alfred Molina, played an Afghan local, too.

Tina insists she raised the issue with casting directors, but they brushed her pleas aside.

Asked how much of a say she had in casting, she told the New York Times, "I had a lot of say."

However, she continued, "If your next question is, why is Chris Abbott not Afghan? - I did beg (the casting directors), 'Guys, my preference would be a native speaker.' They pleaded their case that Chris (was) their choice.

"The tricky thing is, Afghans (can be) Caucasians. (I said), 'Do you really like this guy? Because the only person - the only person! - who's going to get in trouble for this is me.'"

Despite her concerns, Tina admits Chris worked hard to prove he deserved the role.

"He took his work and research so seriously," Tina added. "No one's wanting to make a misstep there."

Margot Robbie, Martin Freeman, and Billy Bob Thornton also co-star in the film.

The news comes amid a serious diversity crisis in Hollywood on the back of the lack of Oscar nominations for people of colour this year (16), and follows outrage surrounding Scottish star Gerard Butler's portrayal of an Egyptian in Gods of Egypt, Welsh actor Christian Bale's role as Moses in Exodus, and Emma Stone, who was cast as an Asian-Hawaiian woman in Cameron Crowe's film Aloha.