Ian Paisley's son Kyle slams DUP over Irish language row
The son of former DUP leader Ian Paisley has accused Gregory Campbell of "shaming unionism" by his mocking of the Irish language.
Kyle Paisley said the remarks went beyond any kind of political statement and were simply ill-mannered.
It came after he branded the East Londonderry MP "a liability" on Twitter.
Mr Paisley also attacked Peter Robinson for defending the comments.
"What he said at the weekend and also what he said in the Assembly previous to that, I think he is shaming unionism, shaming it publicly," he said.
"As a fellow Protestant and a fellow Free Presbyterian, I think it's about time he apologised and pulled his horns in a little bit.
"To use that kind of language, that he could just be completely dismissive of other people's ideology and wishes and aspirations - that is shameful."
The 47-year-old, who is the twin brother of DUP MP Ian Paisley jnr, is a Free Presbyterian minister based in Suffolk.
He is not a member of the DUP, and has been strongly critical of Mr Robinson in the past.
Earlier this year he described the First Minister as a "condescending ignoramus" over his controversial remarks about Muslims.
Yesterday Mr Paisley said it appeared he had learned nothing from that incident.
"I thought Mr Robinson had learned his lesson earlier in the year when he got into controversy about another culture," he added.
"He doesn't seem to have learned his lesson if he can defend a man who's doing a similar kind of thing."
At the weekend Mr Robinson moved to defuse the row by suggesting Mr Campbell's latest comments were "comedy".
However, Mr Paisley, speaking to the BBC's Nolan Show, rejected this.
"I don't know if you were on the receiving end of the comedy that you'd feel like that," he added.
He accused Mr Robinson of making "a major mistake" in backing Mr Campbell.
Some have interpreted Mr Paisley's intervention as the latest stage in a bitter fallout between the Paisley family and the DUP party he founded.