Dramatic finale for American Idol

The pair receive news of the result

Rocker David Cook has beaten teen favourite David Archuleta by a landslide to win American Idol.

In a surprise result, Cook won by a margin of 12 million votes out of the 97.5 million cast by US viewers.

Simon Cowell, one of the show's judges, had told Cook that his song choices handed a victory to Archuleta.

But before the winner was announced, Cowell said the outcome "wasn't quite so clear-cut as we called it" and apologised to Cook.

The 25-year-old victor's three-song set included U2's I Still Haven't Found What I'm Looking For and The World I Know by Collective Soul.

George Michael was one of the show's star guests

But Cook, with his gravelly voice and scruffy style, came in for criticism during the series, particularly from Cowell.

Star-studded

Throughout the run, 17-year-old's Archuleta's fan following and warm praise from the judges was expected to turn him into the show's youngest winner to date.

The final was a star-studded affair, with Canadian rocker Bryan Adams performing with the top six male singers.

George Michael wrapped up the show, singing a medley of hits alongside all 12 American Idol finalists.

Cook said he is remaining realistic despite winning the show and a recording contract.

"I actually walked into this with no expectations and I'm walking out of it with no expectations. This show is a springboard," he said.

Fans of Archuleta said the Utah teenager "will be big no matter what", and admitted his unexpected defeat had "felt like a punch in the gut".