A second UKIP MEP has quit the party in protest at the “extreme nationalist and reactionary” views of leader Gerard Batten.
Bill Etheridge said since Mr Batten became leader in April the party has been increasingly seen as “a vehicle for hate towards Muslims and the gay community”.
His announcement comes less than a week after fellow MEP William Dartmouth announced he was leaving the party, saying Mr Batten was taking it “further and further to the right”.
In his letter of resignation, Mr Etheridge said the party had “irredeemably changed”, with more liberal-minded members leaving and being replaced by those who shared Mr Batten’s views.
He wrote: “The changes you have made since becoming leader have changed the party beyond all recognition.
"You have allowed your personal obsessions free rein. The party is now seen by large swathes of the British public as a vehicle for hate towards Muslims and the gay community.
"While there is a place for extreme nationalist and reactionary views in politics and I defend the right of you and others to hold and express your opinions, I do not believe these were the opinions and policies that Ukip MEPs were elected to represent."
Mr Etheridge, who is an MEP for the West Midlands, said he would continue to sit in the European Parliament as a member of the EFDD Group under the "inspired and rational leadership" of ex-UKIP leader Nigel Farage.
His departure will be seen as evidence of fresh turmoil in the party ranks less than eight months after the previous leader Henry Bolton was ousted following a vote of no confidence at an extraordinary general meeting of members in Birmingham.
In response, Mr Batten called on Mr Etheridge to do the "decent and honourable thing" and resign his seat, returning it to UKIP "to which it morally belongs".
"I am sure the loss of his salary, daily allowance and pension rights would be a small price to pay for a man of principle such as he," he said.
"It was a great pity that Mr Etheridge was unable to make it to the Ukip conference in Birmingham last month where he could have witnessed the party members fully behind my leadership - the people who put him in the seat he currently holds by dint of their efforts and donations."