The European Union and the UK will face "severe consequences" if Britain leaves without a deal, Europe's chief Brexit negotiator has admitted.

Theresa May, the Prime Minister, has said repeatedly that "no deal" is better than a "bad deal" and said that the UK is prepared to walk away from the EU if necessary. On Wednesday she will trigger Article 50 and begin the formal process of leaving the union.

Michel Barnier, writing in the Financial Times, said he wants an "orderly withdrawal" and hopes for an "ambitious free trade agreement" after Brexit.