EU negotiator Michel Barnier urged Britain on Saturday to stop playing "hide and seek" in Brexit talks as the two sides traded blame over the lack of progress in negotiations.
Barnier delivered his warning in a speech just days after the EU dismissed London's latest Brexit plans as "fantasy" following a round of technical talks in Brussels.
British ministers said the barbs were "not helpful" as pressure rises to make progress on the key issue of the future of the Irish border by a June 28-29 EU summit.
"To negotiate effectively, you need to know what the other party wants. A negotiation cannot be a game of hide and seek," Barnier told an audience of EU law experts in the Portuguese capital.
Barnier said that Britain must "look at the reality of the EU in the face, and also the reality of Brexit in the face" and stop making unreasonable demands regarding its future relations with Europe.
The former French minister underlined that Britain had chosen to leave the EU and that recent proposals by London to remain part of certain EU institutions or agencies after Brexit were non-starters.
Barnier said the EU also refused to take responsibility for any bad fallout of Brexit.
"I can see the temptation of the blame game, which would consist in bringing the negative consequences of Brexit on the European Union.
"But we will not be impressed. I won't be impressed," he said.
The heated speech to lawyers detailed the thorny topic of jurisdiction after Britain's official withdrawal from the EU, a highly sensitive topic for pro-Brexiters.
Barnier warned Britain that failing to agree a deal on the governance of a withdrawal treaty which gave primacy to the EU court would torpedo the deal.
He flatly rejected a UK proposal to resolve legal conflicts after Brexit through a joint political committee, instead proposing that British courts remain beholden to the EU court during an 8-year transition.
