UKIP has suspended its leader and three other members after they were accused of stealing data from the party.
An email to all members from chairman Kirstan Herriot said she was "forced to take serious action" against Richard Braine, Tony Sharp, Jeff Armstrong and Mark Dent.
This included reporting them to Action Fraud - though it is not yet known if the police body will investigate.
But Mr Braine denied the allegations, saying the "whole thing was absurd".
Mr Braine - who has led the UK Independence Party since August - told the BBC the incident centred around sending emails.
He accused Ms Herriot and the party's National Executive Committee of denying him permission to send an email out to all of UKIP's members.
Instead, Mr Braine told someone to send an email on his behalf, but it led to him being "falsely accused" of stealing data.
This incident showed the NEC was intent on "culling the list of candidates and removing people that they don't like", added Mr Braine.
But in her email to members, Ms Herriot said she was "acting in accordance with the law" and "protecting our members".
The BBC has contacted UKIP for a response to Mr Braine's comments.
It is not the first time UKIP's leader and its chairman have had a disagreement in public.
In September, Mr Braine did not attend the party's conference in Newport due to "low ticket sales" and called for it to be cancelled.
Ms Herriot said it was a "regrettable decision" by the leader, and called it a "complete insult to the membership".
UKIP has struggled to make an electoral impact in recent years as a succession of leaders has come and gone.
The party came out on top across the UK in the 2014 European elections.
But in May this year, it finished eighth in the polls, losing all its MEPs to The Brexit Party - led by former UKIP leader Nigel Farage.