Hollywood stars dazzled on the red carpet this evening as the 80th annual Oscars got under way.

Actress Nicole Kidman arrives at the 80th annual Academy Awards in Hollywood, the Oscars, February 24, 2008. (Lucas Jackson/Reuters)

A hastily-erected tent protected the actors and actresses as wind and rain threatened to dampen the ceremony on Hollywood Boulevard.

As the Academy Awards show drew near, thousands of fans saw the stars begin to arrive at the Kodak Theatre, where security was tight as police marksmen took up positions on nearby rooftops.

Hollywood's biggest night went ahead after a writers' strike which crippled the entertainment industry and reduced the Golden Globes to a glorified press conference was resolved earlier this month.

Fans screamed as George Clooney led Sarah Larson along the red carpet more than two hours before the ceremony was set to start.

Clooney joked that he never got tired and never had a bad day.

"It's a fun one this time because it's a film we're all really proud of so it's easy to be here and be a part of this," he told E.

Asked why he was so active with various charitable projects around the world, Clooney said: "If you get the opportunity to do it and you don't, I think it's shameful.

"I think it's mostly about waking up and being able to look yourself in the mirror."

He added that he spent Valentine's Day with Larson in Las Vegas.

Among the other early arrivals, Heidi Klum wore a red Galliano dress, which will be sold at auction for charity later, as she went into the theatre with her husband Seal.

British stars among the nominees this year include Daniel Day-Lewis for best actor, Julie Christie for best actress, Tilda Swinton for best supporting actress and Tom Wilkinson for best supporting actor.

Briton Tom Wilkinson, who was nominated for best supporting actor for his role as a lawyer in Michael Clayton, told entertainment channel E: "I thought it was a stupendous script, the whole thing just was intelligent, mysterious, thrilling, and all the things that you want in that kind of script."

He compared working on the film to playing Hamlet and said of the scenes: "In a certain sense they weren't difficult to shoot because it's so well written, it's what you as an actor love to do.

"Great scenes, like playing Hamlet - Hamlet is going through hell but the actor isn't because the lines are so great, and that's true here.

"Very pretentious answer that... sorry, please forgive me."

Asked about his co-star Clooney, he said: "He's got all that packaging and he's a nice guy too.

"He's a wonderful guy, everything about him. He's perfectly produced to do the job that he does do.

"It's very easy for the tensions and stresses of being that kind of wattage of being a mega star... It can really get on your nerves, I'd have thought, but he can handle it."

Wilkinson, wearing a black tuxedo with a grey waist coat, also said he was "addicted" to the TV show Friends and said he was tongue-tied when he met the show's star Lisa Kudrow on Saturday.

Saoirse Ronan, who wore a modest light green dress by Italian designer Alberta Ferretti, walked down the red carpet with her father, actor Paul Ronan.

The 13-year-old Irish star told E: "I never thought I'd even say an Italian name, let alone wear a dress by an Italian designer."

But the Atonement star, who is nominated for best supporting actress, said she did not get nervous when performing with Hollywood actors because "they're all really nice people and they've all become my friends".

One of the ceremony's many presenters, Anne Hathaway wore a red one-shoulder Markesa dress and best supporting actress nominee Amy Ryan arrived wearing a dark blue Calvin Klein dress.

Saoirse Ronan, who wore a modest light green dress by Italian designer Alberta Ferretti, walked down the red carpet with her father, actor Paul Ronan.

The 13-year-old Irish star told E: "I never thought I'd even say an Italian name, let alone wear a dress by an Italian designer."

But the Atonement star, who is nominated for best supporting actress, said she did not get nervous when performing with Hollywood actors because "they're all really nice people and they've all become my friends".

One of the ceremony's many presenters, Anne Hathaway wore a red one-shoulder Markesa dress and best supporting actress nominee Amy Ryan arrived wearing a dark blue Calvin Klein dress.

Pregnant Jessica Alba wore a strapless Markesa dress with Cartier jewellery on the red carpet while Juno star Jennifer Garner wore a black strapless dress with a tail, offset by a large diamond necklace and bracelet.

Cameron Diaz wore a light pink simple off-the-shoulder Christian Dior floor-length dress with Bulgari jewellery.

And best actress nominee Marion Cotillard chose a white Jean Paul Gautier dress, with a fish scale-like finish.

Bafta-winning Briton Tilda Swinton, nominated for the best supporting actress Oscar for her role in Michael Clayton, told E: "I just thought it read like the kind of film that I loved when I started to see grown-up films when I was a kid."

Wearing a black one-sleeved dress, she added that she had never seen the Oscars, had never watched it on the television, and did not know what to expect from the evening.