Blizzard has confirmed that World of Warcraft expansion pack The Burning Crusade won't be released until January now, missing the lucrative Christmas selling season.

The add-on was widely expected to go on sale next month, but Blizzard has opted to extend the closed beta test in order to "further refine the new content that will ship with the game".

Company president Mike Morhaime commented, "We appreciate the enthusiasm surrounding World of Warcraft: The Burning Crusade, and we’re excited about putting the finishing touches on all of the new content.

"We feel confident that the extra time spent polishing the game will result in the high-quality experience that our players expect and deserve."

More information on specific worldwide release dates and pricing will be announced "in the near future".

The news that The Burning Crusade won't be out in time for Christmas is likely to disappoint many WOW fans - but it's unlikely to affect sales of the add-on in the long run. Back in August, Blizzard COO Paul Sams confirmed that the number of subscribers is "over 6.5 million and just shy of seven million" - making for a healthy installed base of potential buyers.