Britain's Foreign Secretary Dominic Raab criticised the European Union on Sunday, accusing it of treating Northern Ireland as a separate country rather than part of the UK.
The comments made as the G7 meet in Cornwall are part of an ongoing row over the Northern Ireland protocol, which became part of the Brexit deal late last year.
"Various EU figures here in Carbis Bay, but frankly for months now and years, have characterised Northern Ireland as somehow a separate country and that is wrong. It is a failure to understand the facts," Mr Raab told the BBC.
Several newspapers reported that French President Emmanuel Macron suggested Northern Ireland was not part of the UK during his meeting with British Prime Minister Boris Johnson.
Mr Rabb accused Mr Macron of undermining territorial sovereignty.
"It is a failure to appreciate what speaking around Northern Ireland in those terms and approaching the issue of the Northern Ireland protocol in those terms does," he said.
"It causes damage to businesses from both communities and that creates deep consternation. We wouldn't talk about Catalonia and Barcelona or Corsica in France in those ways.”
Asked if Britain and Brussels were heading for a trade war, Mr Raab said the bloc needed to permit a free flow of trade between Britain and Northern Ireland, which in turn would allow for “a pragmatic way through".
"What we cannot have is a lopsided approach, built on some of the flawed assumptions ... and which have very real effects for the communities on all sides in Northern Ireland," he said.
Under the post-Brexit deal, the UK agreed to implement border checks on goods moving between mainland Britain and Northern Ireland, effectively leaving the province trading under EU rules.
However, the checks were halted by Britain earlier this year, leading the EU to accuse No 10 Downing Street of reneging on its international commitments.
Sections of the British media called the row the "sausage war" because it affects the movement of chilled meat.
Mr Johnson on Saturday said his government would do "whatever it takes" to protect its territorial integrity in the trade dispute and warned the EU that Britain would implement emergency measures if no solution were found.
"I think we can sort it out but ... it is up to our EU friends and partners to understand that we will do whatever it takes," he said.
The diplomatic spat threatened to cast a shadow over the G7 meeting in southwest England, with speculation that even US President Joe Biden would be dragged into the debate.
On Wednesday, trade discussions in London between Brussels and Britain came to nothing but both sides agreed to hold more talks in the near future.