"No Country For Old Men" took early Oscar prizes for best supporting actor and adapted screenplay, cementing its position as the frontrunner in the 80th annual Academy Awards.

Escaping a threat from the screenwriters strike, the Oscars show kicked off Sunday in front of the glittering royalty of the movie world.

"This town has been torn apart by the writers strike," said host John Stewart. "But I'm happy to say the fight is over."

Javier Bardem won best supporting actor for his role as a killer leaving a trail of death across the American West.

"It's a great honour for me to have this," said the Spaniard. Marion Cotillard of France won the Oscar for best actress for her performance in La Vie en Rose.

Filmmakers Joel and Ethan Coen, brothers who write and direct together, won for best adapted screenplay, dedicating the award to novelist Cormack McCarthy.

"Thanks for bringing us this novel and giving us the opportunity to make this movie," said Ethan Coen.

British Indie stalwart Tilda Swinton won the Oscar for best supporting actress Sunday night in Hollywood for her performance in Michael Clayton. She dedicated the award to her US agent, who she insisted looked exactly like the famous statuette.

The first prize of the ceremony, the Oscar for costume design, went to "Elizabeth: The Golden Age". The prize for best-animated feature film went to the Disney-Pixar comedy "Ratatouille".

Earlier, thousands of film fans and celebrity watchers braved rainy conditions to watch stars, including George Clooney, Cameron Diaz, Jessica Alba, Daniel Day Lewis and Jennifer Garner, turn up in all their finery for the annual gala.

The red carpet outside the Kodak Theatre was covered with a huge plastic canopy to protect what has in recent years turned into the most-watched fashion show on earth.

The dour conditions in normally sunny Southern California reflected what is widely considered to be the grimmest slate of Oscar nominees in recent years, headed by best-picture favourite "No Country For Old Men", a bleak tale of violence in the American West.

The other top nominees - "There Will Be Blood", "Atonement" and "Michael Clayton" - are also bleak.

The only exception is coming-of-age comedy "Juno", which is the highest-grossing contender at the box office, with US ticket sales of more than $120 million.

"This year has a slate of Oscar- nominated psychopathic killer Hollywood movies. Thank God for teen pregnancy," said Stewart.

Made on a shoestring budget, Juno triumphed at Saturday's Independent Spirit Awards, with three prizes including best film. The story of a teenager who falls pregnant has emerged as a dark horse in the Oscars race.

"No Country For Old Men", which stars Josh Brolin, Tommy Lee Jones and Javier Bardem, has scooped more prizes than any other in the run- up to the Academy Awards.

The relative lack of box-office success among the top movies has raised fears that the broadcast could register an all-time low in the ratings.

But with all the stars on parade, Oscars producer Sid Ganis was confident that the event would be a success, after earlier shows like the Golden Globes were squelched by the winter's just-ended strike by Hollywood writers.

"Not only have there not been any awards shows, but I think there's a good solid buzz about the strike being over (and) everybody back to work," Ganis said.