Under fire by both ABC and gay leaders, Isaiah Washington has apologized for what he called his "unacceptable in any context" comments about gay co-star T.R. Knight at Golden Globe Awards Monday night.

"I can neither defend nor explain my behavior," Washington said in a statement, according to People. "I can also no longer deny to myself that there are issues I obviously need to examine within my own soul, and I've asked for help."

Apologizing to "T.R., my colleagues, the fans of the show and especially the lesbian and gay community," Isaiah Washington said he "marred what should have been a perfect night" for Grey's Anatomy and hurt both Knight and "everyone who has struggled for the respect so many of us take for granted.

"T.R.'s courage throughout this entire episode speaks to his tremendous character. I hold his talent, and T.R. as a person, in high esteem. I know a mere apology will not end this, and I intend to let my future actions prove my sincerity," Washington said.

Washington, who plays Dr. Preston Burke on the hit ABC show, denied in the pressroom at the Golden Globes on Monday that he ever used a gay slur in reference to Knight.

"No, I did not call T.R. a faggot," said Washington. "Never happened, never happened."

But during an appearance Wednesday on The Ellen DeGeneres Show, Knight said that Washington did use the word during an on-set argument with co-star Patrick Dempsey in October.

"He referred to me as a faggot," he told DeGeneres. "Everyone heard it."

Neil Giuliano, president of the Gay & Lesbian Alliance Against Defamation (GLAAD), said Thursday night that Washington "has scheduled a meeting with us for early next week, and we look forward to exploring opportunities for moving forward and healing some of the wounds of the past four months."

Earlier GLAAD had demanded that Washington apologize for his actions. Some fans have also circulated a petition online to have the actor fired.

ABC has responded by saying that Washington's remarks at the Golden Globe Awards were unacceptable and are being addressed.

"We have a long standing policy to create and maintain respectful workplaces for all our employees," the network said in a statement.

"We dealt with the original situation in October, and thought the issue resolved. Therefore, we are greatly dismayed that Mr. Washington chose to use such inappropriate language at the Golden Globes, language that he himself deemed 'unfortunate' in his previous public apology. We take this situation very seriously. His actions are unacceptable and are being addressed."

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.