Former minister Dominic Raab has said during negotiations with the EU senior figures implied losing Northern Ireland was the price the UK would pay for Brexit.
Speaking on Sky News, Mr Raab said he had been surprised at the EU's attitude toward the province and the view it could "carve up" the UK.
The former Brexit secretary said it had come from "people around" the head of the EU's civil service Martin Selmayr.
Mr Raab served as Brexit secretary for four and a half months, taking over David Davis, before resigning last month in protest at the deal reached between Theresa May's Government and Brussels.
"You would hear swirling around in Brussels - particularly the people around Selmayr, Martin Selmayr in the Commission, and some others - that losing Northern Ireland was the price the UK would pay for Brexit," said Mr Raab.
"This was reported to me through the diplomatic channel.
"It is one thing to defend your interests robustly, but there is another thing in the spirit of so-called European unity to be trying to carve up a major European nation.
"And it is deeply reckless if you look at the Europeans own interests… look at Catalonia, look at the seperatist tendancies across Europe. Look at Belgium. This kind of stuff looks like politics, a very narrow politics trumping the European, let alone the UK interest."
A controversial figure, Martin Selmayr has been the Secretary-General of the European Commission since March of this year.
Nicknamed 'the monster' by his boss Jean-Claude Juncker, the EU's ombudsman issued a damning verdict in September on the manner in which his appointment was made, with the EU's Ombudsman Emma O'Reilly saying the process "stretched and possibly even overstretched the limits of the law".
Mr Raab also said in the interview that the EU should have been tougher during negotiations, particularly in relation to the backstop.
"I want a good, positive, optimistic Brexit and I think we can still turn this around," he added.