London CNN  — 

UK Prime Minister Theresa May said Friday that negotiations with the European Union were “at an impasse” after a disastrous summit at which her Brexit plan was largely rejected.

May struck a defiant tone during a Downing Street statement in which she called for the EU to “respect” the British position and the result of the June 2016 referendum.

A day after returning from the summit in Salzburg, Austria, she called on the EU to spell out its objections to her plan or come up with an alternative.

“Throughout this process, I have treated the EU with nothing but respect. The UK expects the same. A good relationship at the end of this process depends on it,” May said.

UK Prime Minister Theresa May, France's Emmanuel Macron, left, and other leaders at the summit.

Downing Street had hoped the informal Salzburg summit would pave the way to a resolution of outstanding issues in Brexit talks before a formal meeting in October. Instead, the leaders of the 27 remaining EU nations were unexpectedly resolute in their opposition to the UK leader’s proposals.

Donald Tusk, president of the European Council, said key aspects of the plan, agreed at the Prime Minister’s Chequers country retreat in July, “will not work” in their current form.

French President Emmanuel Macron went even further, saying that the entire Brexit project was sold to the British people by “liars” who immediately fled the stage, unwilling to see their project through.

In her Downing Street statement, May refused to budge and said the ball was in the EU’s court. “At this late stage in the negotiations, it is not acceptable to simply reject the other side’s proposals without a detailed explanation and counterproposals,” she said.

“So we now need to hear from the EU what the real issues are and what their alternative is so that we can discuss them. Until we do, we cannot make progress. In the meantime, we must and will continue the work of preparing ourselves for no deal.”

Tusk trolls May

May appeared bruised by the reception she got in Salzburg, and sounded particularly withering when referring to the European Council president. “Yesterday Donald Tusk said our proposals would undermine the single market. He didn’t explain how in any detail or make any counterproposal. So we are at an impasse,” she said.

Tusk drew attention Thursday for an Instagram post in which he appeared to troll May. An image of Tusk offering pastries to May is captioned: “A piece of cake, perhaps? Sorry, no cherries.”