Robert Pattinson found it difficult to film a series of gay sex scenes for the forthcoming movie Little Ashes, the film's director has revealed.

Paul Morrison told the LA Times the Twilight star found the nude scenes “harder” than his co-star Javier Beltran.

Rob, who plays Salvador Dali in the movie, and Javier, appear in two underwater scenes together – one in clothing and one without.

“Yeah, what happens is that Dali recalls that scene later on, after Lorca's death, and in his memory they're not wearing underwear,” Morrison said.

“So there is a nude scene, tastefully shot, of course."

Rob plays an 18-year-old Dali in the movie just as the surrealist painter arrives at university in Madrid.

It is during his studies when Dali encounters Federico García Lorca, played by Javier, and the pair strike up an intimate relationship.

“I think they were difficult, but I think all sex scenes are difficult, and for all actors of all ages,” Morrison said.

“And I find them difficult, certainly, to direct, and ... you have to get very intense about them, and as a director be clear as to what you're looking for so they know that they're acting and they're not doing it.

“And I think Rob probably found it harder than Javier, to draw the line between performance and, ah, but that was also in the nature of the part, that Dali's sexuality was so complicated, complex and mysterious, I think even to himself, and his fear of sexuality, and if you're playing that role, that kind of rubs off on you, so I think sex and pain were so closely entwined with Dali that to play those scenes is also hard, and the triangle sex scene is an unbelievably difficult scene.”

Morrison admitted that the “jaw-dropping” success of Twilight had come at a good time for Little Ashes, which is released later this month.

Robert Pattinson