The surfing accident was just one in a series of memorable events surrounding the filming of The Great Raid - a movie set in the Philippines during the second world war, when more than 500 American prisoners were liberated by a group of elite Rangers and Alamo Scouts, who took the initiative when the US government had all but turned its back on them.

'The whole exercise gave us an insight into the horrors those men went through,' says Fiennes. 'They died of torture and malaria - the death rates in those camps was high. Just that psychology, confronting that day-to-day knowledge, must have been hugely damaging.'

Fiennes joined a cast that includes Benjamin Bratt, James Franco and Connie Nielsen. He plays Major Gibson, a figurehead to the hundreds of sick and starving men in the Cabanatuan PoW camp, and who himself was stricken with malaria. To prepare for the role, he and other cast members endured a rigid diet regimen, which he says he was able to get through by thinking of the men he and his group were playing. That, he says, and a few laughs.

'The humour kept us intact, spirited and focused,' he says. 'It was gruelling, but we used comedy to survive the situation. At times, though, it felt like psychological warfare.'

Such as when he and the other actors playing emaciated war prisoners would watch as crew members helped themselves to huge portions of food from the catering cart. 'And there we were, with our lettuce leaf and grain of rice,' he says.

They exercised several hours a day, including a mixture of cycling, swimming and running, and he lost more than 9kg for the role. Throughout, he says, he was motivated by the true stories of the soldiers they were playing, as told in historical books such as The Great Raid on Cabanatuan and Ghost Soldiers.

'The drive was honouring that generation of men who lay down their lives for the freedoms we like to experience today,' he says. 'For an actor, it's a great challenge. When I read the script, I felt that the PoWs' story was the soul of the movie. They were the ghost soldiers. They were hanging on. For an actor to step up and portray that, I was excited by the challenge and, ultimately, what I learnt through that challenge.'

That said, Fiennes says he's a pacifist at heart. 'I can't get excited about the loss of human life, especially civilian life. I would like to think that we could have a dialogue before violence, and that we should fight for dialogue. This war was 60 years ago, which gives us time to reflect, and God knows we need pause and reflection. My understanding of second world war history is focused on Europe and the invasion of fascism and Nazi ideology, and halting that invasion seems absolutely right. But where my place in the world is now - I see it's very complicated.'

Although he and his co-stars didn't meet any of the PoWs, they studied reams of documentary footage. 'If you think about it, 60 years wasn't all that long ago. It was our father's and grandfather's generation, and what's interesting about that generation is they don't usually open up about that subject matter.'

Fiennes is very much the thinking woman's Hollywood sex symbol, one of People magazine's 50 sexiest stars, yet he gives the impression that, although he doesn't shun the limelight, he doesn't strive for it, either. Certainly, there's more of a cerebral quality to Fiennes' work, which can be attributed largely to his training and background, and to the fact that the theatre and the arts run in his family.

Born in Salisbury, Wiltshire, in 1970 as the youngest of six - his mother was the late novelist, Jini Fiennes, his brother Ralph is an actor and his sister Martha a director - Fiennes was brought up in West Cork, Ireland. After art school, he worked with the Young Vic Youth Theatre, then went to the Guildhall School of Music and Drama. He made his professional stage debut in The Woman in Black in the West End, and also spent a couple of seasons with the Royal Shakespeare Company.

Work came fairly easy to him when he arrived in Hollywood, playing Robert Dudley in Shekhar Kapoor's Elizabeth with Cate Blanchett in 1998, and a young William Shakespeare in the Oscar-winning Shakespeare in Love that same year.

He travels between Los Angeles and London, and is fortunate enough to be working pretty steadily. Upcoming releases include Running with Scissors, based on Augusten Burroughs' autobiography, which ended filming a few months ago. Fiennes' co-stars include Annette Bening, Gwyneth Paltrow and Alec Baldwin.

'I saw a beautiful rough cut and thought it was superb,' he says. 'It was refreshing, witty, subversive, dark, funny, tragic. I cried and I laughed. I thought all the characters did the most brilliant performances.'

Also coming up is The Darwin Awards with Winona Ryder, in which he plays a forensic detective investigating some- one who might accidentally kill himself.

In between his projects, Fiennes says he's looking forward to getting back into surfing - undeterred by his accident.

'It's amazing when you feel the power of the wave,' he says. 'I can understand the addiction.'

The Great Raid opens on October 20