The film, which follows mouse-like Pikachu and friends as they battle a bio-engineered enemy, had the most successful opening for a cartoon.

The Rugrats Movie set a three-day opening weekend record last year

Pokemon: The First Movie continues to ride a wave of Pokemon popularity fuelled by young children.

The craze began in 1986 when Pokemon - which is a blend of the words "pocket" and "monster" - was launched in Japan as a Nintendo video game. It then evolved into a trading card phenomenon and a TV series.

An American version of the show now airs several times a week on the Warner Bros network as the highest-rated children's series on television.

"Pokemon couldn't be hotter than it is right now," said Paul Dergarabedian, president of Exhibitor Relations, which tracks the box office.

"Kids are insatiable for entertainment and they'll consume everything that comes out in a big way," he added.

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Pokemon opened to sell-out crowds in more than 3,000 US cinemas on 10 November, becoming the biggest Wednesday opening for any animated film in history.

Warner Bros said it was also the biggest Wednesday opening in any November for any release industry-wide.

The big-name rivals it has outpaced include Disney's The Lion King and A Bug's Life, plus Paramount's The Rugrats Movie.

However, Pokemon is not likely to hold onto its No 1 spot after 24 November, when the long-awaited Toy Story 2 is released by Disney.

Children's craze

Pokemon has set a new standard, explains US cultural history professor Tim Burke. "Pokemon is a cultural phenomenon, not just a toy fad. It's inescapable, it's everywhere."

Shortage: LA mum-of-four Ruth Alhaj is trying to collect the 57 Burger King Pokemon toys

The success of the film has been boosted by a promotional blitz, especially a $22m (£13.75m) campaign by Burger King.

The fast-food giant has been distributing 57 toys - eight per week - over two months. Children get a Pokeball when they order a Kids Meal or a Big Kids Meal.

But even Burger King has been overwhelmed - some of its 8,000 restaurants have run out of the toys, much to the dismay of children and parents.

But what has been driving kids especially crazy is a collection of trading cards launched by Nintendo, which owns the rights to the Pokemon gold mine.

In the UK, Pokemons are expected to fend off the opposition to become the end of the millennium's must-have item, according to the British Association of Toy Retailers.

The £7.99 electronic dolls, which speak their names when stroked or spoken to, are already flying off the shelves, set to become the No 1 Christmas toy.