KEIRA Knightley last night unveiled her new movie Atonement as she led the British charge at the Venice Film Festival.

The 22-year-old stars in the adaptation of Ian McEwan's novel and her performance is already being talked up as Oscarworthy.

She plays Cecilia Tallis, an upper class beauty whose fledgling love affair with the housekeeper's son (James McAvoy) is destroyed by a tragic misunderstanding.

Atonement's world premiere in Venice last night was the curtain-raiser for the festival and is being hailed as one of the strongest British films in years.

Much has been made of her slender figure, which she showed off yesterday in a figure-hugging navy and white dress. But the actress warned that appearances can be deceptive.

"What this film shows is the danger when the line between fiction and fact gets blurred, " she said.

"Magazine pictures, for example, are fiction. One person has done the make-up and hair, it's somebody else's clothes, it's choreographed by someone else.

"In the media it's very important to see different varieties of people - old, young, whatever size. As a woman myself I want to see variety. Hopefully that will happen more."

Knightley played down her Oscar chances, saying: "As far as awards go, that's neither here nor there.

Atonement was a complete gift. I read the script and I cried. Any script that makes you cry is worth pursuing."

She said of her screen character: "I fell in love with Cecilia totally and utterly, partly because of the romance. I love a bit of romance."

But her co-stars were full of praise for her performance. McAvoy said: "I was blown away by Keira.

The amount of poise and grace she has is incredible."

Atonement is directed by Joe Wright and is only his second film. His first, Pride and Prejudice, also starred Knightley.

The period drama begins in 1935 and moves through the Second World War.

Its most impressive scene is a recreation of the evacuation of Dunkirk, which was filmed on the beach at Redcar, using 1,000 local men as extras.

The film also marks the big screen debut of 13-yearold Saoirse Ronan, who is being hailed as a major talent of the future.

Ronan plays Cecilia's sister, a young girl whose over-active imagination leads to tragedy. Vanessa Redgrave plays the character as an older woman.