Revenues generated by World of Warcraft in China rose by more than 20 per cent last year, according to The9 Ltd which licenses the game from US-based publisher Blizzard Entertainment.

The9 declared revenues of $175.4m in 2007, suggesting that a copyright infringement case filed against Blizzard and The9 by a local firm has had little impact on the bottom line.

The9 had previously attributed more than 98 per cent of its revenue to Warcraft, but reported that several new games are now bringing in significant income.

"Our solid financial results were mainly due to strong growth of player usage of Warcraft with The Burning Crusade expansion pack, as well as a new revenue source from commercialisation of Granado Espada in late November," said Jun Zhu, chairman and chief executive at The9.

"In the fourth quarter of 2007, we attained aggregate peak concurrent users of approximately 1.2 million for games that are currently in commercial operations, and as of December 31 2007 we had over 33.4 million total registered users."

The company has also begun testing FIFA Online, a multiplayer online soccer game.

Following a complaint from Founder Technology Group that its fonts had been used in the Chinese edition of Warcraft without permission, The9 recalled some Warcraft installation discs in the fourth quarter of 2007.

The financial impact of this recall appears to have been negligible. However, Founder had claimed more than $13m in damages in a court case filed in August 2007 and it is unclear whether this case has been resolved.