The hacker collective Anonymous on Monday appeared to publish the identities and contact information for alleged members of the Ku Klux Klan (KKK) before a social media account affiliated with the self-styled “hactivist” group denied releasing any such data.

The purported release comes ahead of Thursday’s Million Mask March, a demonstration in which supporters of the hacker collective are expected wear its signature Guy Fawkes mask and gather in front of city halls around the world.

Twitter accounts affiliated with Anonymous, including @YourAnonNews, released the first batch of about 80 names, phone numbers and email addresses of alleged KKK members on data-upload site pastebin.com.

The data alleges that among the KKK’s ranks are several U.S. mayors and senators.

Knoxville, Tennessee Mayor Madeline Rogero, whose name appeared on the list, refuted allegations that she’s affiliated with the KKK.

"Don't be ridiculous,” she said. “I began my political career working for the rights of farm workers with Cesar Chavez. I have spent decades working for causes of social justice and equality."

Anonymous-affiliated social media accounts said last week that the collective obtained a list of 1,000 members from a compromised KKK member Twitter account.

"All will be revealed next month around the one year anniversary of #OpKKK," it tweeted, under the handle @Operation_KKK.

However, later on Monday that same Twitter account denied releasing the first batch of names and contact information.

“This account has NOT YET released any information. We believe in due diligence and will NOT recklessly involve innocent individuals,” a tweet said.

A subsequent tweet read: “We respect the work of our fellow freedom fighters. However, we are unable to confirm, deny or take credit for any work that we did not do.”

The tweets from differing accounts caused confusion among supporters and critics, who are still uncertain about the authenticity of the initial release.

Anonymous took action against the KKK in November 2014 after members of the white supremacist group threatened violence against peaceful protesters in Ferguson, Missouri.

The Midwestern town has become a flashpoint for racial tensions in the United States since the police shooting of unarmed black teen Michael Brown in August 2014.

In a statement earlier this week, Anonymous said it felt justified in "applying transparency" to the KKK.

"You are more than extremists. You are more than a hate group," the statement released online said.

"You operate much more like terrorists and you should be recognized as such. You are terrorists that hide your identities beneath sheets and infiltrate society on every level,” the hacker collective said.

"The privacy of the Ku Klux Klan no longer exists in cyberspace. You've had blood on your hands for nearly 200 years."

The statement threatened to release the names of up to 1,000 KKK members and associates by Thursday.

Anonymous claimed to have taken down a KKK-linked Twitter account in November 2014, and released the identities of a number of Klan members.

Al Jazeera and Agence France-Presse