In a launch usually reserved for blockbuster movie premieres Microsoft rolled out the red carpet at London's IMAX theatre last night to celebrate the arrival of Halo 3.

American celebrities Pharrell Williams and Christian Slater were in attendance to entertain fans gathered outside in the rain. UK TV presenter Iain Lee hosted the show inside the cinema.

Williams took part in a head-to-head online battle in the game against other celebrities attending launch parties dotted around Europe, including LL Cool J in Amsterdam and Carmen Electra in Paris.

The audience was then split in half and a champion selected for each side. The winner could secure a copy of Halo 3 for everyone in their half of the audience.

Unfortunately the battle was disrupted by technical problems, at which point Microsoft offered a copy of the game to everyone in the audience.

Further problems marred the launch of the final part of the Halo trilogy, following reports that some Halo 3 Limited Edition discs were scratched rendering the game unplayable.

Microsoft has acknowledged the problem and promised to replace any scratched Halo 3 disc free of charge until the end of the year.

Those affected will need to return the disc along with a form which can be printed out from Microsoft's Xbox Disc Replacement Program website, but customers have been warned to allow up two weeks for delivery of the replacement.

Worldwide pre-orders for Halo 3 reached around 1.5 million, and Microsoft expects sales to top £70m in the first day alone.