Historical thriller 300 is based on a real battle in 480 BC

The story of the 300 Spartan soldiers who battled a large Persian army will be the most successful March release ever if early figures are confirmed.

Biker flick Wild Hogs starring John Travolta and Tim Allen moved down to second, taking $28m (�14.4m).

Youth fantasy Bridge to Terabithia was third with Zodiac and Ghost Rider joint fourth, both making $6.8m (�3.5m).

If 300's estimated takings are confirmed, it would break the March record set by Ice Age: The Meltdown, which took $68m (�35m) in its first weekend last year.

NORTH AMERICAN BOX OFFICE 1. 300 ($70m) 2. Wild Hogs ($28m) 3. Bridge to Terabithia ($6.9m, above) 4. Zodiac ($6.8m) 4. Ghost Rider ($6.8m) Source: Media by Numbers

More people went to see 300 at the weekend than the rest of the top 10 combined.

300 has grabbed attention not just for its graphic violence but also its extensive use of computer generated effects and backgrounds.

Eddie Murphy's larger-than-life comedy Norbit came in sixth with $4.3m ($2.2m), followed by the Jim Carrey thriller The Number 23, with $4.2m (�2.1m).

Music and Lyrics, a romantic comedy with Hugh Grant and Drew Barrymore, took eighth spot, while spy thriller Breach, based on real-life FBI spy Robert Hanson, was ninth.