Officials at Marvel Studios came under fire when the Caucasian actress was first cast as Doctor Stephen Strange's mentor, a comic book character from Tibet.

Swinton recently tried to clear up the controversy by insisting her new character is not Asian, and is, in fact, a whole new take on The Ancient One.

"It's not actually an Asian character - that's what I need to tell you about it," she told The Hollywood Reporter last week (ends22Apr16). "I wasn't asked to play an Asian character, you can be very well assured of that. You just have to wait and see, because it's not an Asian character."

Swinton had to keep further details about her role under wraps, but now Marvel chiefs are speaking out to put to rest accusations of 'whitewashing' once and for all.

In a statement released on Wednesday (27Apr16), Marvel executives wrote: "Marvel has a very strong record of diversity in its casting of films and regularly departs from stereotypes and source material to bring its MCU (Marvel Cinematic Universe) to life."

"The Ancient One is a title that is not exclusively held by any one character, but rather a moniker passed down through time, and in this particular film the embodiment is Celtic," they continued.

"We are very proud to have the enormously talented Tilda Swinton portray this unique and complex character alongside our richly diverse cast."

Doctor Strange screenwriter C. Robert Cargill has also explained his new take on the character, insisting the original comic book portrayal was a "racist stereotype". He also suggested filmmakers wanted to detach The Ancient One from its Tibetan roots in an effort not to offend Chinese censors, due to ongoing political tensions between the two nations.

"He originates from Tibet, so if you acknowledge that Tibet is a place and that he's Tibetan, you risk alienating one billion people," he added during a recent interview on podcast Double Toasted.

Doctor Strange, which stars Benedict Cumberbatch as the titular superhero, is set for release this autumn (16).

Diversity in Hollywood has become a hot topic in recent years. Emma Stone faced a backlash last year (15) after she featured as an Asian Air Force liaison officer in Aloha, while fans have expressed disappointment in Scarlett Johansson's casting in an upcoming film adaptation of Japanese manga comic Ghost In The Shell.