An extensive membership list of the far-right British National Party (BNP) has been stolen and leaked online.

The BNP has confirmed that the list from November 2007 has been leaked, but said that some addresses have been added since then.

The list contains 10,000-12,000 names, addresses, phone numbers, email adresses and additional information, and was posted on a Google blog for a short while before being taken down.

"Detailed analysis by our membership department proves conclusively that the core list dates from between 30 November and 2 December 2007," said BNP leader Nick Griffin.

"We have already sent formal demands to the web hosts to remove the list, pointing out to them that the publication of this year-old list constitutes contempt of court because a court order preventing its release or use was made and consented to by the group of disgraced former employees who first misappropriated it."

Analysis of the members, all of whom have to be 'indigenous Caucasians' under party rules, has reportedly found 16 serving and more than 50 former soldiers, several police officers (who are barred from joining by law) and overseas members in California, Ireland and Saudi Arabia.

The publication of the names has sent the membership into a panic, according to postings on the NorthWestNationalists blog.

"I've just had a call, I'm on it too," wrote one anonymous poster. "I want my f****** member money back, like has been mentioned here, I could lose my f****** job. I'm bloody angry."

A serving soldier also expressed disbelief and called for Nick Griffin to stand down. "Me too, I'm on the list, I could be chucked out of the army. What is going on? Piss up in a brewery comes to mind. I want some answers, NOW," he w rote.

The leak is almost certainly the work of an insider, and highlights the dangers of not protecting important data from prying employees. While there are numerous technologies to do this, very few organisations implement them.