Ian Paisley has accused the SDLP's Claire Hanna of being capable of "nothing more than name calling" after she referred to him as "professional troll".
Speaking on BBC Radio Ulster's Nolan Show on Thursday Ms Hanna took aim at Mr Paisley's argument that the UK should invoke Article 16 of the Brexit Withdrawal Agreement and set aside the Northern Ireland Protocol.
In response the DUP MP said that she should consider her role in public life "if she can't respond to a message and can only name call".
Speaking at Westminster's Northern Ireland Committee on Wednesday Mr Paisley urged the UK Government to suspend the protocol, saying it has been an "unmitigated disaster" for businesses.
Under Article 16 the protocol can be suspended if it causes "serious economic, societal or environmental difficulties that are liable to persist, or to diversion of trade".
Ms Hanna said the DUP and Mr Paisley must face up to their own role in Brexit.
She said that her party did not love the protocol but that it was an "attempt to clean up a mess not of our making".
Referring to Mr Paisley's comments at the committee Ms Hanna accused him of "having a tantrum".
"This probably has more to do with internal DUP issues and winding up Arlene Foster," the South Belfast MP said.
"Ian Paisley is now essentially a professional troll. He's very good at it, he's very articulate, he's very experienced.
"He has no interest in taking responsibility and solving problems."
In a statement the North Antrim MP noted that his South Belfast counterpart "has form" for calling him names.
Ms Hanna was previously criticised for referring to Mr Paisley as a gob****e on social media in 2019 after comments he made in relation to then-Prime Minister Theresa May.
"If I were to be unprofessional and call her names such a 'fish wife' it wouldn’t add to the debate just make me look silly and suggest I had no case to make. So I don’t do that. She needs to get out of the playground and be a serious politician," the DUP MP said.
"She needs to address the consequences of supporting a protocol that has damaged trade. Little wonder she is angry."
Mr Paisley told the Nolan Show that the DUP's parliamentary group supported the invoking of Article 16.
The North Antrim MP said he would be "very surprised" if anyone within the DUP disagreed with his view.
However when asked if it was DUP policy Mr Paisley replied that the view hadn't "been formulated or written down into a manifesto or voted on".
He said senior DUP figures at Westminster including deputy leader Nigel Dodds, Sammy Wilson, Westminster leader Sir Jeffrey Donaldson and others felt the article should be invoked as soon as possible.
Mr Paisley said he would be "very surprised" if party leader Arlene Foster didn't support the stance.
However, he admitted he had not asked Mrs Foster her view on the matter as he hadn't "had a chance".
Speaking on Thursday morning Mrs Foster said her party needed to use all the available ways to highlight the difficulties of the protocol to the UK Government and push for solutions.
The First Minister said she would raise her concerns during a meeting with Chancellor of the Duchy of Lancaster Michael Gove on Thursday.
Mrs Foster said the protocol was causing "difficulties that we warned of last year and of course we will continually raise the operation of Article 16 of the protocol and how it can be triggered and what level of harm, frankly, needs to be in place for it to be triggered."
"Those conversations will be ongoing," she said.