Photographs of the actress and her castmates in tops emblazoned with the legend "I'd rather be a rebel than a slave" appeared in British magazine Time Out London last week (ends04Oct15).

The words are taken from a quote by iconic women's rights activist Emmeline Pankhurst, who is played by Meryl in the new film, but the shoot has sparked an outcry among human rights campaigners.

In the U.S., the term "rebel" was often used to refer to those who fought to preserve slavery on the Confederate side during the American Civil War.

Kevin Powell, a prominent African-American activist and author, has now warned the photoshoot's reference to slavery may undermine its message of equality.

"I think my white sisters and brothers like Meryl Streep, no matter how famous or talented, need to understand that slavery or references to slavery is not something to take lightly," Powell tells WENN,

"It is one of history's great crimes against humanity, and we still feel the effects of it, in America, in Europe, across the planet, here in the 21st century. While I am very much an ally to women and girls in the work for equality on all levels, I think we've got to be mindful of dissing others while calling for our own freedoms. What might be oppression to one group can easily become privilege and enthusiastic ignorance to another group."

Priscilla Igwe of U.K. organisation The New Black Film Collective adds, "It is a little bit ill informed and ill judged. We don't have a monopoly on slavery, slavery still exists today. But in this atmosphere one has to err on the side of caution when using certain trigger words."

John Downie of the Society for the Advancement of Black Arts says, "I understand that people may be upset by this but maybe we should understand the context that Emmeline Pankhurst was coming from."

Suffragette is set to premiere at the BFI London Film Festival in the British capital on Thursday night (07Oct15).