Former 'Grey's Anatomy' star Isaiah Washington has alleged that racism was a factor in his sacking from the hit medical drama series after he twice used an anti-gay slur.

In an in-depth interview with Newsweek, published on the magazine's website, Washington spoke at length about the events leading up to his firing from the show.

During an argument with his co-star Patrick Dempsey Washington used an offensive term to refer to his fellow co-star TR Knight; the term was later repeated by Washington backstage at the Golden Globes.

The actor said: "Patrick and I had a philosophical disagreement that got out of hand and that I regret a great deal. I said a lot of negative things that were never reported, but there was one word that caught everyone's attention, particularly someone who wasn't even in the room with us. It was a fight between two men that shouldn't have happened. But someone heard the booming voice of a black man and got really scared and that was the beginning of the end for me. I see that now, but I didn't then."

Washington, who attended counselling following the incidents, said that he did everything the makers of 'Grey's Anatomy' asked of him to atone for his outbursts.

"I apologised and showed my remorse for what I said and for the pain I caused anyone," said the 44-year-old.

Washington cited ignorance for his remarks: "Growing up in the South, I wasn't exposed to as many different lifestyles and personalities as I could have been. And that's always a problem, because the more you're exposed, clearly the more you know and understand. My mother had several cross-dressing friends who she sometimes referred to with names I'd never use, but she didn't know any better. There was no hate, just lack of awareness."

On his allegations of racism as a factor in his sacking, Washington also said: "Well, it didn't help me on the set that I was a black man who wasn’t a mush-mouth Negro walking around with his head in his hands all the time. I didn't speak like I’d just left the plantation and that can be a problem for people sometime."

He continued: "I had a person in human resources tell me after this thing played out that 'some people' were afraid of me around the studio. I asked her why, because I'm a 6-foot-1, black man with dark skin and who doesn't go around saying 'Yessah, massa sir' and 'No sir, massa' to everyone? It's nuts when your presence alone can just scare people, and that made me a prime candidate to take the heat in a dysfunctional family.''

He concluded: "My mistake was believing that I would get the support from my network and all of my cast mates across the board. My mistake was believing I could correct a wrong with honesty and sincerity. My mistake was thinking black people get second chances. I was wrong on all fronts."