The 'Chinese Empire' blends feverish writing by an unknown author, bits of martial arts epics, extracts from other fantasy works such as Lord Of The Rings, and random characters from Chinese literature with the Hogwarts characters.

Neil Blair, Rowling's legal adviser, said: "We are aware of this one and we are taking action both through the local courts and by negotiating with the authorities in China to prevent violation of copyright. We are very pleased with the co-operation we are receiving from the authorities there."

Mark Lambert, the chief executive officer of the Scottish Book Trust, said: "It's not actually an issue of money, in this case, but it's an issue of intellectual copyright and theft of the idea and using JK Rowling's name in this way. And she is right to be concerned about this and to be taking action.

"This kind of thing, unauthorised sequels, has been happening before now. For example Star Trek fans write their own episodes online, as a tribute to the series. But this is very different, these volumes are being sold on the streets in order to profit from the name."

Margaret Smillie, a copyright lawyer with Bannatyne Kirkwood France and Co in Glasgow said: "Copyright law around the world is pretty much the same wherever you go, only the terminology will change. But while launching a case like this in another country can be done it's a very complex, expensive and involved process. Only someone like JK Rowling would be able to afford something like this."