Source: ReutersRobert Pattinson

Robert Pattinson thinks he looks like a "blob".

The Twilight star admits he can't understand why girls find him attractive, despite regularly appearing in lists of the world's sexiest men, and is astonished he used to be booked for modelling assignments.

"I feel like a cartoon character. I look like an idiot - one of my legs is slightly longer than the other.

"I was such a terrible model. I was really tall but still looked like a six-year-old," he said.

The 23-year-old British actor admits that his insecurities make it difficult to cope with life as one of Hollywood's hottest celebrities.

"I'm unbearably self-conscious about stuff. I'm trying not to drown. I guess I'm not the type of guy cut out to do a franchise. I'm not much of a crowd person," he said.

However, when Pattinson landed his role as vampire Edward Cullen in the Twilight franchise, director Catherine Hardwicke admits she had her work cut out in making him look attractive.

"They called me up and they literally said, 'Catherine, do you think you can make this guy look good?' So I said, 'Here's what I'm going to do. I'm going to get his hair back to a different colour, do a different style. He would work with a trainer from now on. My cinematographer is great with lighting. He will study the cheekbones, and I promise you, we'll make the guy look good'?" She told Vanity Fair magazine.

Pattinson has previously said he doesn't care about being praised for his looks.

"The hottest actor stuff doesn't really mean anything. You have a month maybe with all this heat and hype," he said earlier this year.