Superman actor Routh was chosen from hundreds of hopefuls

Superman "is probably the most heterosexual character in any movie I've ever made," said Singer.

The issue has been debated in gay magazine The Advocate, the Los Angeles Times and on entertainment websites.

Singer's new film stars Brandon Routh, who takes over the role following the death of Christopher Reeve in 2004.

Rather than reinvent the character's appearance, director Bryan Singer - who directed two X-Men movies - has kept the cartoon superhero's cape, red tights and blue body suit.

Some of the speculation over the sexuality of Singer's hero has focused on his appearance in promotional posters.

But Singer said his version of the superhero was a "very romantic icon" - handsome, virtuous and vulnerable.

Paul Levitz, president and publisher of Superman owner DC Comics said: "We were all scratching our heads. He's not a gay character."

In the movie, Superman comes back to Earth after a five-year absence to find that Lois Lane - his true love - has a new boyfriend and a child.

Superman Returns opens in the US on 28 June and in the UK on 14 July.