U.S. actor Kevin Costner on Saturday said his Bodyguard co-star Whitney Houston was almost overlooked for the role because of her color and lack of acting experience.

Costner told the singer's funeral service that while he thought Houston was perfect for the part of pop star Rachel Marron, the movie's producers cautioned that a white and more experienced actress might be more suitable.

"The red flags came out immediately. Maybe I should think this over a bit," Costner said, noting that though Houston was at the height of her fame as a singer, she had yet to appear on the big screen.

"We could also think about another singer, was a suggestion. Maybe somebody white. Nobody ever said it out loud, but it was a fair question," Costner recalled.

"I told everyone that I had taken notice that Whitney was black. The only problem was, I thought she was perfect for what we were trying to do.

"There was a bit of a relief in the room when we found out that Whitney was going to be on tour and she wouldn't be available for our movie. The anxiety came right back when I said we should postpone and wait a year."

But "to their credit," movie producers Warner Brothers backed Costner's instinct, he said.

The film went on to become an international blockbuster, although not before Houston had overcome her own doubts about taking on the role, including the use of a screen test.

"The day of the test came and I went into her trailer after the hair and make-up people were done.        

“Whitney was scared. Arguably the biggest pop star in the world wasn't sure if she was good enough.

"She didn't think she looked right. There were a thousand things to her that seemed wrong. I held her hand and told her that she looked beautiful. I told her that I would be with her every step of the way," Costner said.

Houston even aborted the first take after only a few lines of dialogue and returned to her trailer before regaining her composure and trying again.

"A half hour later, she went back in to do her screen test and the studio fell in love with her.

“The Whitney I knew, despite her success and worldwide fame, still wondered am I good enough?" Costner said.

And the movie's hit track I Will Always Love You, arguably Houston's signature song, almost never came to be, the actor told the service.

"It wasn't supposed to be in the movie. The first choice was going to be What Becomes of a Broken Heart? but it had been out the year before in another movie and we felt that it wouldn't have the impact," Costner said.

"I urge us all inside and outside, across the nation and around the world, to dry our tears, suspend our sorrow and perhaps our anger just long enough, just long enough to remember the sweet miracle of Whitney," he added.