Scots actor James McAvoy has admitted he was terrified filming sex scenes with Angelina Jolie for his latest movie.

One of Hollywood's hottest young stars, he lines up opposite Angelina in Wanted, a film based on Mark Miller's explosive novels.

He plays 25-year-old account worker Wesley Gibson, who is transformed from a loser, cheated on by his girlfriend and bullied by his boss, into a dark superhero.

But despite having starred opposite Keira Knightley in Atonement and now Angelina, James says he doesn't enjoy the sex scenes, however convincing they may seem on the big screen.

He said: "It's sweaty and uncomfortable.

"My paranoia is the girl I'm doing the sex scene with will think I'm getting off on her.

"I have nightmares about that the night before a sex scene. There's no chance of getting any kind of stimulus because you're so nervous and there's all these people watching you.

"It's daunting. They're considered to be the most beautiful people in the world, and I'm clearly not. I don't think I've been hit by the ugly stick, but I'm not exactly a matinee idol."

Having got up close and personal with Kiera, he is quick to shoot down rumours she has an eating disorder.

"She's really not anorexic," he insisted.

"I've felt every part of her in many scenes in Atonement and she is fine. There's meat on those bones, I guarantee you."

Helped by the stunning visualist director Timur Bekmambetov - creator of the most successful Russian film franchise in history, the Night Watch series - Wanted sees James in his first action role.

He said: "The director was nuts, his head was in a different universe. It's a very weird and interesting big action flick, an adventure story and a big visual ballet. It's a bit of wish fulfilment.

"It was great fun. Wesley is a flawed hero, the opposite of Robbie in Atonement, who always reacted to what was happening.

"Wesley is totally apathetic, nearly clinically depressed.

"He has been manipulated by the government, by his family and at work.

He wants to free himself from it all." He added: "Angelina and I share one epic snog, which was kind of weird. Her life is mad with all the attention she gets, but she still retains a really approachable air. She's lovely, actually. We had a good laugh on a fairly demanding shoot, because it was so physical."

Regarded as Hollywood's new It boy, and having celebrated his 29th birthday earlier this week, his film star status has taken him a long way from Glasgow's Drumchapel housing estate, where he was brought up.

Famously, it was only after actor-director David Hayman addressed James's school and the 16-year-old offered to make tea on his next film that he got his first break. Four months later, Hayman rang to ask him to audition for a part in 1997's The Near Room.

The role, as the son of a pimp, led to a stint at the Royal Scottish Academy of Music and Drama. From small TV parts in The Bill and Band Of Brothers, he got his big break with the series Shameless, on which he met his future wife, actress Anne-Marie Duff, who is eight years his senior.

He played the faun Mr Tumnus in Chronicles Of Narnia and the doctor who falls under Idi Amin's spell in The Last King Of Scotland, before Atonement brought him international fame. But he says he feels sorry for some of today's stars who've become heartthrobs almost overnight.

He said: "I've been doing this for a long time but it gave me time to learn by taking small roles, then middling ones, and a huge amount of character roles.

"Atonement was the first straight-up leading man I've played. I feel sorry for someone like Orlando Bloom. He was immediately a movie star and did not have the chance to do work where nobody really noticed him. I'm glad I've had a slow climb and was allowed to explore what acting is.

"I didn't ask to become an actor or anything like that. I just asked if I could come and make his tea.

"He shouldn't have given me the part. I was bad in it. But David Hayman changed my life. I hope I get to thank him some day by being good in something for him.

"I didn't do any acting again for a few years. Then I thought I'd try to get into drama school. I managed that but I still wasn't entirely set on being an actor."

Despite his uncertainty, he paid for his lessons at the Royal Scottish Academy of Music and Drama with a job filling cakes in a supermarket.

He said: "For two years, I ran straight from the early shift at Sainsbury's bakeries to the 8am warm-up."

And his first major TV role left him plagued by self doubt. "During Shameless, I was struggling to find out the truth about myself. I drank a lot and sat around eating junk food," he recalled.

"I thought I was a bit of a fraud because I felt I'd fallen into acting. I was only doing it because someone had given me a job - for others it was their vocation. I felt I was lying to myself and about what I wanted in life.

"It was Anne-Marie who taught me how to respect life, and it took my career to a whole new level.

"I used to be negative, but when I realised that, I decided to get on with it."

Brought up by his grandparents and his mum, he refuses to meet his father, who walked out on the family.

"I can't be bothered with it," James admitted. "Lots of people are brought up in slightly unusual circumstances.

"With the breakdown of marriage which has happened more since the Seventies, we're the first generation that have really become normal with that. It's not like we all need to go into rehab because of it. I had a fantastic upbringing.

"If I was less secure in myself, I might be more interested. But I know what made me, I know why I am the way I am. I don't need to go hunting for missing answers."

Mixing with thespians on both sides of the Atlantic has, however, all but rid him of his broad Glaswegian accent.

"It has chilled out a lot in the past eight years or so, when English people couldn't understand me sometimes, and Americans just couldn't get it," he said.

"I'm from a working-class environment, but I am no longer working class. It was a tough upbringing, but my life felt normal.

"Having little money, you get sensitive to the world around you at an earlier age than you would have otherwise.

"That's helped as an actor.

"But, originally, I wanted to join the Navy and later to become a priest: both offered a chance of escape."