Police officers, teachers and soldiers were among the 12,000 names listed, as well as children. Addresses, telephone numbers, email addresses and jobs were also included.

Several BNP members based in the Lancaster district were among those on the list. An injunction banning publication of the document was quickly put in place.

Lancaster Unity, an internet-based campaign organisation set up three years ago to protest against far-right groups including the BNP, received more than 120,000 hits on Wednesday after news spread across the internet.

Ketlan Ossowski, who runs the Lancaster site, said: "We were sent the information that the list was available so we did an article explaining the type of person on the list and it was in the public domain, but we refused to spread the list, mainly because children were on it.

"There are a lot of people in the firing line now because of this and quite rightly so. This breach of data security is bad for the BNP."

The site usually has around 3-4,000 hits a day, but activity went through the roof after links were posted on blogs worldwide.