The West Midlands MEP elected in triumph last year is taking her former party to court over claims they victimised her for being a lesbian.
Nikki Sinclaire has launched two court actions against UKIP, which she also accuses of treating her unfairly because she refused to join a right-wing group.
The party withdrew the whip from her in the European Parliament and excluded her from standing as the general election candidate in Meriden.
Ms Sinclaire was elected as UKIP’s second West Midlands MEP in 2009, in a result which was seen as a breakthrough for the party. It meant UKIP had more MEPs in the region than Labour or the Liberal Democrats.
But she is now taking action against them in the High Court and an employment tribunal following a series of high-profile rows.
In January this year she resigned from the right-wing Europe of Freedom and Democracy grouping in the European Parliament, which UKIP was part of.
She said she was concerned about the views held by some of the other parties in the group, which she considered to be anti-semitic and homophobic.
Ms Sinclaire continued to be a member of UKIP but the party then withdrew the whip, effectively excluding her.
She was also prevented from standing as a UKIP candidate in this year’s general election, although she eventually stood as the candidate of Solihull and Meriden Residents Association.
Ms Sinclaire will claim in court that she was subject to a “campaign of intimidation” even though no formal disciplinary proceedings were taken against her.
And the MEP, who is openly gay, will also claim there is “deep-rooted homophobia” within UKIP itself.
Her lawyer Paul Daniels, a partner with legal firm Russell Jones & Walker, said: “Our client has been the subject of a series of unlawful actions by UKIP, including barring her from standing in the general election, in breach of UKIP procedures, following her decision not to remain a member of UKIP’s alliance with a host of extremist and far right wing parties in the European parliament. This issue is to be the subject of a major High Court claim, to be issued shortly.
“Ms Sinclaire has now been forced to bring additional discrimination claims, to draw to public attention the prejudices that are present within certain parts of UKIP and its leadership . These prejudices need to be challenged so that all members are treated respectfully and fairly.
“Ms Sinclaire remains dedicated to the cause of UKIP, but will fight for equal opportunities for all, including the rights of minority groups as well.”
Ms Sinclaire added: “My unlawful removal as a UKIP candidate, was caused by my standing up for my principles and against political extremist, including homophobia. In addition, I have been repeatedly discriminated against and treated unfairly by UKIP compared to others because of my sexuality.
“It is unacceptable in the 21st century for people to be marginalised and treated in an offensive and derogatory way on the grounds of their sexuality.
“This behaviour needs to be exposed, so that the party can move forward and I can get on with representing the people of the West Midlands and their causes, which I am so passionate about.”
A spokesman for the UK Independence Party said: “Independent MEP Nikki Sinclaire had the UKIP whip withdrawn in March this year. As she has stated her claims against the party are the subject to legal actions and it would be inappropriate for us to comment at this time.”