Heath Ledger refused to allow the Academy Awards to joke about Brokeback Mountain, Jake Gyllenhaal has revealed.

In director Ang Lee's 2005 film, Gyllenhaal starred opposite Ledger as two ranch-hands in love working in 1960s Wyoming.

The film received a “Best Picture” nomination but lost in the category to Crash.

“I mean, I remember they wanted to do an opening for the Academy Awards that year that was sort of joking about [Brokeback Mountain],” Gyllenhaal told UK glossy Another Man.

“And Heath refused. I was sort of at the time, 'Oh, okay … whatever.' I'm always like: It's all in good fun.”

“And Heath said, 'It's not a joke to me – I don't want to make any jokes about it,'” Gyllenhaal added.

Before his tragic death in 2008 at 28, Ledger defended the movie, saying it was about love.

“We're showing that love between two men is just as infectious and emotional and strong and pure as it is with heterosexual love,” Ledger said during a press junket for the film. “And if you can't understand it, just don't go see the movie. We don't care.”