Former French armed services minister Sylvie Goulard accused the UK of allowing ideology to get in the way of “pragmatism”.
It comes as concerns in Paris and Berlin are building over divisions within the UK Cabinet.
Speaking on Newsnight, Ms Goulard said: “You know what, I am puzzled because the British diplomats are always pragmatic and aware of their own interests.
“So be, what you are used to be and we will have a deal. But please leave some of the uncertain grounds you are sometimes using now where ideology is replacing pragmatism and sense for the self-interest.
“I hope that we avoid a crash. It will not be good for the UK, it will not be good for us but it would also not be good for the world and I insist on that.”
The former French minister even likened the UK to a “rogue state” and stressed that the UK and France must follow the law.
She continued: “France and the UK are two permanent members of the UN security council. We are supposed to promote the rule of law worldwide.
“How can you ask rogue states to respect the rule of law if we are not able to find a compromise and an agreement between us?”
It comes after Theresa May and European Commission President, Jean-Claude Juncker, met for dinner yesterday evening to discuss the acceleration of Brexit talks.
Days before, EU negotiator Michel Barnier said the negotiations were deadlocked over the size of the UK’s payments.
A statement released after last night’s dinner on behalf of both parties said the meeting had seen a “broad, constructive exchange” and agreement the pace of negotiations should increase in the coming months.
It said: “As regards the Article 50 negotiations, both sides agreed that these issues are being discussed in the framework agreed between the EU27 and the United Kingdom, as set out in Article 50 of the Treaty on European Union.
“The Prime Minister and the President of the European Commission reviewed the progress made in the Article 50 negotiations so far and agreed that these efforts should accelerate over the months to come.
“The working dinner took place in a constructive and friendly atmosphere.”
However, it gave no indication of when the EU will finally move on to the second phase of talks where trade and the future relationship will be discussed.
After the fifth round of discussions were brought to a close last week, Mr Barnier said he would not recommend that talks move on to the next stage when he attends the European Council on Thursday.
But Conservative MP for Fareham, Suella Fernandes, believes that the UK has made a lot of progress with negotiations.
Speaking to Newsnight she said: “I think the Prime Minister made a very constructive and generous offer in Florence and I do think that puts the burden and the responsibility on the EU to respond in a similarly constructive way.
“It is clear that progress has been made on EU citizens, on the Irish border and I think building on that progress is a good start for where we are now.”