Tory MP Jacob Rees-Mogg has said that people claiming Brexit could lead to a return to the Troubles in the North are "almost encouraging violence".
The arch-Brexiteer also suggested the Republic could quit the single market and customs union in favour of UK regulation in order to make Britain's EU withdrawal smoother.
Mr Rees-Mogg branded warnings that Brexit could pose a threat to peace in the North as "cynical".
He told The House: "I think it's a politically unappealing and cynical approach to suggest that violence may be a consequence of not doing what the pro-Europeans want, and they should think whether that is a wise approach to take.
"Once you start proposing that violence may be a consequence of something, you're almost encouraging violence. So, people making that argument should think very carefully about the wisdom of that argument."
Asked about Theresa May's pledge to work closely with the EU to solve border issues like regulatory alignment, the MP said: "I think the Prime Minister was being generous to the European Union in that context.
"She wants to have friendly relations in the negotiations, but it's a question of nuance and I think they're the stick in the muds in this and have come up with a solution that is wholly impossible for the United Kingdom to accept, that we should take Northern Ireland out of the United Kingdom.