Mr Barnier has insisted that all the main causes of concern to do with Brexit, lies with the United Kingdom and “no one else” in an angry blast of words.
The EU Brexit chief negotiator hit out at Mrs May for her shambolic and not providing a “clear position” for Britain’s future relationship with the bloc.
Mr Barnier told Vice News: “It is the decision of the British to leave the union that has created the problem. No one else. Nothing else.
“What is sometimes hard for the British to understand is that we don’t want to negotiate, we don’t want to compromise on who we are.
“They want to leave, it is their choice to leave.”
He then added: “It’s not only about negotiating between officials in Brussels or London, it’s about the people, about the business, about the stakeholders.
I think that this negotiation cannot be secret.”
Mr Barnier questioned UK’s relationship with the EU post-Brexit, saying he had “no certainty” about their future relations.
He added: “My work is not finished.”
“The first step is setting the terms of this divorce.”
“But the most important thing is our future relationship, which will last for many years, that’s the important part.”
“Right now, I have no certainty.”
“I can see the difficulty and the intensity of this debate.”
During a meeting with members of the EU’s Brexit steeering group, he said: “Given the rather volatile British political situation, I recommend that we remain very united and clear about our objectives and principles.”
Many within the pro Brexit ranks are concerned that EU officials are holding the UK to ransom, particularly over the Irish border issue. It has leave supporting ministers questioning why Britain is still not walking away, especially after such volatile language from the European side.