In a remarkable statement from Downing Street, May blames Brussels for "impasse," just weeks ahead of a deadline to seal a deal – and six months before Britain leaves the EU in March.
Prime Minister Theresa May hit back Friday at the European Union after it roundly rejected her Brexit plan, saying its refusal to compromise was "not acceptable" and warning she was still prepared to walk away from the talks.
In a defiant statement from Downing Street, May blamed Brussels for the "impasse" just weeks ahead of a deadline to seal a deal – and six months before Britain leaves the EU in March.
"Throughout this process, I have treated the EU with nothing but respect. The UK expects the same," the prime minister said.
May was speaking after returning from an EU summit in Salzburg Thursday, where her fellow leaders lined up to condemn her proposals for post-Brexit trading ties and the Irish border.
It was a setback characterised by the British media as a "humiliation," just days before a meeting of May's Conservative party, where eurosceptics are ramping up the pressure on their leader to be tough.
Standing at a podium with two British flags behind her, May said: "At this late stage in the negotiations, it is not acceptable to simply reject the other side's proposals without a detailed explanation and counter proposals.
"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."
She said she wanted an agreement, but "I have always said no deal is better than a bad deal".
The pound slipped against the euro after she spoke, reflecting fears that Britain could crash out of the EU with no agreement.
EU Council President Donald Tusk hit back late Friday at May's criticism of the EU's negotiating position: "The results of our analysis have been known to the British side in every detail for many weeks."
"The UK stance presented just before and during the Salzburg meeting was surprisingly tough and in fact uncompromising," he said in a statement.
Tusk added he remains "convinced that a compromise, good for all, is still possible" in Brexit negotiations and that he is "a close friend of the UK and a true admirer of PM May."
EU leaders had previously criticised May's proposal for a free trade area in goods after Brexit, but the tough tone at the Salzburg summit surprised many commentators, with some describing it as an "ambush."
Tusk and French President Emmanuel Macron said it would fragment the bloc's single market and "not work", and demanded she come back with an alternative by an EU summit in mid-October.
The bloc also raised the stakes by putting on ice a special summit planned for November to seal a deal, saying it would only happen if there is progress next month.
On Friday, May said the EU's plan for Britain to stay in the European Economic Area, effectively the single market without any say in the rules, would "make a mockery" of the 2016 vote for Brexit.
Meanwhile the alternative offer of a free trade agreement was contingent on a "backstop" keeping British-ruled Northern Ireland aligned with EU rules, which she warned risked the integrity of the UK.
This was "something no British prime minister would ever agree to" she said, adding: "If the EU believe I will, they are making a fundamental mistake."
She repeated that she would bring forward alternative proposals to the backstop, which would come into effect until a new trade deal is struck.
Reports suggested a tetchy meeting between May and Irish Prime Minister Leo Varadkar on the sidelines of the summit in Salzburg had helped harden views.
Varadkar said Friday the two sides were "entering into a rocky patch" but said he was determined to secure a deal.
EU Commission chief Jean-Claude Juncker said the two sides were "moving closer" but were like "hedgehogs who love each other".
"When two hedgehogs embrace, they have to watch out that they don't get scratched," he told the Austrian daily Die Presse.
Simon Usherwood, politics professor at the University of Surrey, said the EU's previous strategy of giving May some breathing room at summits had "collapsed."
Salzburg was "about irritation and bad tempers that the UK really hasn't got the measure of this properly," Usherwood added.
But he noted that May was "super-constrained by the party. She can't really be seen to be making concessions."
The House of Commons must approve any Brexit deal, and May's small majority would be undermined if her hardline Brexiteer lawmakers go through with a threat to oppose it.
Eurosceptic Tories welcomed May's tough tone on Friday but reiterated their own opposition to her trade plan, which they think will undermine Britain's independence.
Opposition Labour leader Jeremy Corbyn said the prime minister's negotiating strategy had been a "disaster."
"The political games from both the EU and our government need to end because no deal is not an option," he said.