The leader of Ukip has been accused of a “complete insult” after he decided to boycott his own party conference due to low ticket sales.

Richard Braine has pulled out of the conference after fewer than 450 tickets were sold for the two-day event. The party was hoping to attract double the amount of delegates to the event in Newport, south Wales, later this month.

In the latest furore to engulf the party infamous for its public spats, the Ukip chair, Kirstan Herriot, wrote to all members stating new leader Braine had attempted to cancel the conference due to a potentially low turnout.

In the email sent to all members, Herriot, backed by Ukip’s ruling national executive committee (NEC), said Braine’s stance had been a complete affront to “hard-working” party members. She confirmed the conference would go ahead despite Braine’s no-show.

She wrote: “Both I and the NEC believe it is a complete insult to the membership to attempt to cancel conference because of a potentially low turn out. It is also a particular affront to hard-working regional, county and branch officers who have worked hard in encouraging members to attend conference to hear Richard lay out his vision for the future of Ukip. It is therefore a particular shame that he has decided not to do this.”

In order to increase delegate numbers, the party said it had now decided to offer some free single-day tickets and those who had paid for their one-day ticket would be offered a refund.

Herriot’s email added that Braine was still welcome to take his “rightful place” on the conference stage should he have a “change of heart”.

Ukip has suffered a slump in the polls following the rise of the Brexit party, which was founded by Nigel Farage after he quit Ukip over the former leader Gerard Batten’s anti-Islam views and links to the far-right activist Tommy Robinson.

Ukip’s ruling NEC blocked Batten from standing again for the leadership, but his ally Braine was elected by the membership instead. In a vote of members with a turnout of about 25%, Braine received 53% of the vote.

When contacted by the Guardian, Braine said he would not be commenting, saying only that it was an internal decision by the chair to contact party members. However, in an email to Ukip members, Braine confirmed his decision, saying he had been informed by the party treasurer that it was facing a “very low turnout” for its conference.

Braine said he had proposed moving the conference to a venue in north-east England and called for Batten to be reinstated to the party. He claimed the NEC had been misinformed about the number of attendees, with the real number being much lower.

He wrote: “I have made clear to the chairman and NEC that I would not attend unless something drastic was done to increase ticket sales, namely returning Gerard Batten to good standing to heal the rift with the many members who are boycotting conference for that reason, and installing one of the two candidates I have put forward to be chairman.”

Braine claims his advice was rejected.