Gemma Arterton was "depressed" when she first watched 'Prince of Persia: The Sands of Time'.

The actress - who plays the female lead Princess Tamina in Disney's latest blockbuster - was unhappy when she viewed the film for the first time because she feared she looked out of place in such a big movie.

She said: "I was really unhappy. I remember seeing the film and thinking 'Wow, this is amazing and epic and beautiful', and then seeing myself in it and thinking, what the hell am I doing in it? I just found it really weird, and I was a little depressed about it. Every insecurity you have is amplified on a huge screen. I can't watch things more than a couple of times, because I find it too strange. I wasn't always this way. In 'St Trinian's' I didn't care. But that's changed."

Although the 24-year-old star enjoyed her time with cast and crew, she couldn't take the job seriously without panicking because it had such a big budget.

She explained to Stylist magazine: "My first day on set was a shock - the sets were huge and the producers spent thousands of dollars on my costumes. But I think I would have freaked out if I took the job too seriously, so I would muck about and have fun on set.

"I never saw 'Prince of Persia' as a big fat deal that would make me into a massive movie star, which is what certain people have said. It's funny, it is a pivotal moment, but without putting it down, I think the most significant moments in my career were smaller films that challenged me, like 'The Disappearance of Alice Creed' and 'Tess Of The D'Urbervilles'."