The EU's chief negotiator said that the United Kingdom government's position made it clear that the United Kingdom is leaving both the Customs union and the Single market, and this would not allow "frictionless trade".
Michel Barnier also doubted whether Britain "fully understood" the consequences of its vote to leave the European Union in March 2019. He goes on to try to kill off the chatter about setting up "a customs union" (a bespoke arrangement like Turkey has with the EU) emphasising that such a set-up keeps customs controls and other checks in place as is far from the "frictionless" trade talked about by United Kingdom ministers.
He said in French, "This is why the 27 member states and the European Parliament are seeking an agreement".
He added that leaving "the single market and [building] a customs union to achieve "frictionless trade" is also "not possible".
At a speech at the European Economic and Social Committee in Brussels, Mr Barnier said that after Brexit the United Kingdom will become "a third country" and that businesses should prepare for the uncertainty.
Reflecting on the UK's vote to leave the European Union, he said: "The decision to leave the European Union has consequences and I have to explain to citizens, businesses and civil society on both sides of the Channel what those consequences mean for them".
The EU's chief negotiator repeated hardline comments that Britain will be worse off after we quit the bloc, despite David Davis' wishes to get the "exact same benefits" as being in the single market.
Labour leader Jeremy Corbyn revealed he is to have an "extended meeting" with Mr Barnier next Thursday to discuss his party's position on Brexit, in what was seen as a further attempt to depict the opposition party as a "government in waiting".
He advised business leaders to "assess, with lucidity, the negative consequences of the UK's choice on trade and investment". And of course no spirit of revenge.
Mr Barnier tells businesses to prepare for disruption ahead but you can't help thinking as you read it that he may be actually urging them to lobby their politicians to stop Lancaster House Brexit from happening.
Barnier explained that a "frictionless trade" would only be possible with "the combination of the customs union and the rules of the internal market".
He went on: "Let me be clear, these consequences are the direct result of the choices made by the United Kingdom, not by the EU".
Britain and the European Union must avoid a no deal situationMr Barnier added that failure to reach a Brexit trade deal would mean "a return to the distant past", with trade regulated by World Trade Organisation rules which would impose tariffs on goods.
Since the inconclusive general election deprived May of her majority, critics of the "no deal" scenario have gained strength.