Hacktivist group Anonymous has begun publishing the email addresses and phone numbers of alleged Ku Klux Klan (KKK) members, an extremist white supremacy organisation in the United States.

According to an Anonymous website, the list – which is unverified – includes four senators and mayors of major cities in the U.S.

The details were published via Pastebin, a website where text can be stored online for a set period of time.

The anarchist collective released a statement on Nov. 1 saying that it had shut down servers and accessed personal information of KKK members, and that on Nov. 4, a “Twitter storm” would occur to “spread awareness about the operation.”

“And on the 5th we shall release more than 1000 Ku Klux Klan members’ names and websites, new and old.”

November 5, which is Guy Fawkes’ Day, is also when the collective’s planned “Million Mask March” will take place. The March expects to see demonstrators wearing Guy Fawkes' masks around the world protest against austerity, corrupt politicians and mass surveillance - a scene familiar to anyone who has watched the film "V for Vendetta".

The feud between Anonymous and KKK began after the latter reportedly threatened to harm Ferguson, Missouri protestors in 2014. Anonymous then launched "Operation KKK" to shut down the Klan.

As U.S. politicians named in Anonymous’ leak quickly stepped forward to deny any affiliations with the KKK, a Twitter account for Operation KKK also distanced itself from the lists.

The account has since named Twitter user, Amped Attacks as the man behind the release. The user told Tech Crunch that he had spent nine days gathering and verifying the information that was gathered.

“I got the information from several KKK websites when I [hacked] them and was able to dump their database. I went through many emails that was signed up with these sites and a few of the emails that sparked my interest was the ones of the politicians in question there would be no reason for them to be signed up on any KKK website unless they supported it or was involved in it.”

Meanwhile, the leader of a well-known KKK chapter has called the list of leaked identities a “bogus.”

Speaking to TIME, national director of the Knights of the Ku Klux Klan Thomas Robb said that while it was possible some data from minor KKK chapters was leaked, membership data are kept on separate computers that are “immune to Internet hacking.”

“One computer is right here in my house and it’s not connected to the Internet. I’m looking at it right here,” Robb said. “The other computer is at the main office just down the road, and it’s the same way: not connected to the Internet.”

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