I, Robot took $53.3m (£28.4m) in its opening weekend, making it Smith's best debut, despite turns in blockbuster hits Men in Black and Independence Day.

Spider-Man 2 slipped a place, with receipts of $24.2m (£12.9m), taking its US total to $301.7m in 19 days.

Teen star Hilary Duff's A Cinderella Story debuted at number three.

I, Robot's opening week triumph proves Will Smith still has the star power to pull in audiences.

"He's just so likable, he takes something like science fiction, which can be a little cold, and he makes it warm and entertaining."

'Mr July'

The film, inspired by author Isaac Asimov, sees Smith play a detective in 2035 who suspects a robot has committed murder - despite assurances it is impossible for them to hurt humans.

"(Smith) is Mr July," said Paul Dergarabedian, president of box office tracker Exhibitor Relations.

"He's the perfect summer action star. He's a guy who seems like somebody fun to hang out with, but you know the guy can kick some butt when he has to."

Fourth in the box office chart was Will Ferrell's news spoof Anchorman: The Legend of Ron Burgundy, with $13.4m (£7.1m).

Fifth was Michael Moore's controversial documentary Fahrenheit 9/11. Its weekend takings of $7m (£3.7m) took its US total to $98.8m (£52.7m).