A "Queer Question Time" in Birmingham was delayed for more than 30 minutes by a UKIP candidate who was arrested after refusing to leave.
Prospective Parliamentary candidate for Halesowen & Rowley Regis Ms Nicole Sinclaire said the three-party debate on gay issues hosted by Birmingham Pride Community Trust was "undemocratic".
Ms Sinclaire made a dramatic last-minute entrance to the debate at Birmingham's Hippodrome Theatre and demanded she be included in the event which involved representatives from the three main political parties.
Clare Short, former International Development Secretary and candidate for Ladywood, was joined on the panel by Conservative candidate for Sutton Coldfield Andrew Mitchell, Shadow Minister for Home Affairs and Liberal Democrat candidate for Selly Oak, Dr Richard Brighton.
Organisers tried to persuade Ms Sinclaire to leave the theatre but they were forced to call on five police officers who were greeted with wolf whistles by the audience as they removed the UKIP candidate from the theatre and arrested her.
The debate, on the impact of gay issues on the election and how parties should respond to them, continued without incident. Trust chairman Steve Bell was unruffled by the UKIP protest and emphasised that it did not spoil the event.
He said: "It is inconceivable that we could have had this kind of debate with representatives of the three main parties 10 years ago. In some marginal constituencies the gay vote will win or lose the election.
"We gave UKIP the opportunity to take part as long as the other representatives agreed, which we found out they did at the last minute, but Nicole threatened to issue a press release about it if we did not invite them anyway so we decide to withdraw the invitation rather than bow to the pressure.
"You have to ask yourself where do you draw the line with fringe parties and if we had not we could have had up to seven people here which would have been too many."
A UKIP spokesman said: "Nikki Sinclaire was arrested for trying to speak at a political meeting. She was asked to leave by the Tory candidate, and then by the organisers of the meeting. She stood her ground."
Ms Sinclaire is political assistant to UKIP Deputy Leader Mike Nattrass.