Keira Knightley’s new movie Atonement was unveiled today, as she led the British charge at the Venice Film Festival.

The 22-year-old stars in the adaptation of Ian McEwan's wartime novel, and her performance is already being called Oscar-worthy.

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 has been chosen as the curtain-raiser for the Venice Film Festival and is being hailed as one of the strongest British films in years.

But Knightley, in Venice to see the film compete for the Golden Lion, 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."

"I fell in love with Cecilia totally and utterly, partly because of the romance. I love a bit of romance."

Her co-star James McAvoy was full of praise for Knightley’s performance: "I was blown away by Keira. The amount of poise and grace she has is just 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 Wright captured in a single steadicam shot.

The scene was filmed on the beach at Redcar, Cleveland, using 1,000 local men as extras.

Wright explained: "It started as a joke, really. I wasn't quite sure how I was going to film this montage as I only had one day to do it in. I joked we'd do it in a single shot and the joke became a serious proposition.

"We had these wonderful extras, 1,000 men from the local area who had been brought together. We rehearsed from 6am to 6pm. We did three takes and on the fourth take the steadicam operator collapsed. Everyone put their hearts and souls into it, including those 1,000 men on the beach."

The film also marks the big screen debut of 13-year-old 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.

The schoolgirl from Ardattin, Co Carlow, made her acting debut aged nine in RTE TV series The Clinic, and Atonement is one of four major movies under her belt which are all set for release in the coming months.

She plays Michelle Pfeiffer's daughter in I Could Never Be Your Woman, appears in Death Defying Acts with Catherine Zeta Jones and The Christmas Miracle of Jonathan Toomey with Joely Richardson, and has just started shooting sci-fi film City of Ember with Tom Hanks and Bill Murray.

Asked if she had any advice for her young co-star, Knightley said: "I take advice from Saoirse, I wouldn't dream of giving it to her!"

McAvoy added: "She's got her head screwed on, she's incredibly talented and her mum and dad are amazing. I think she'll be fine."

The cast will be on the red carpet tonight for Atonement's world premiere.

This year's film festival features a particularly strong line-up of British contenders.

They include Sleuth, a remake of the 1972 whodunit directed by Kenneth Branagh with Jude Law and Michael Caine in the title roles; It's A Free World - Ken Loach's study of migrant labour in the UK; and Nightwatching, Peter Greenaway's Rembrandt mystery starring Martin Freeman.

The winning film and prizes for best director, actor and actress will be announced on September 8.

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