BNP leader Nick Griffin claims the leak is part of a smear campaign
BNP leader Nick Griffin has said a document claiming to list thousands of his members is a "malicious forgery".
The list, which included former senior military figures, academics and doctors was posted on the WikiLeaks website.
It follows the leaking of a BNP membership list containing 10,000 names and addresses in November 2008.
In a statement on the BNP website Mr Griffin said the new one included parts of the old list, thousands of unknown names and "made up" membership details.
The names, addresses, home and mobile telephone numbers of apparent party members are listed in the spreadsheet posted on WikiLeaks.
But Mr Griffin said after examining the list he could say "unequivocally" it was not genuine: "It is a concoction of the old list plus a number of inquiries received, but, most disturbingly, it contains thousands of names of people with whom the BNP has had no contact whatsoever."
"The list includes thousands of people with renewal and membership numbers next to their names which are totally false and made up.
"We have no idea from where this information has been drawn. Some of it looks like random items drawn from a telephone book."
He claimed the leak was part of a smear campaign against the party ahead of his appearance on BBC One's Question Time programme on Thursday.
Wikileaks, which was founded in 2006 by a group of dissidents and journalists, allows whistleblowers to anonymously post documents on the web.
A former BNP member was fined £200 by Nottingham magistrates in September after admitting publishing the membership list released in 2008.