EU’s chief negotiator Michel Barnier speaks to the media in Brussels, Belgium. (Photo: AFP/ VNA)

In an email to member states seen by The Independent, Michel Barnier said the proposal unveiled by Mr. Johnson on Thursday was “unacceptable” as it crossed red lines laid down by EU leaders. In the email, Mr. Barnier told member states that the demands contained in the “rather combative” statement by Mr. Johnson were very clearly a no-go.

Boris Johnson used his first House of Commons statement as prime minister to demand the complete removal of the so-called Irish backstop as the key objective in future Brexit negotiations with the EU. Mr. Johnson insisted he would accept no version of the Northern Irish backstop, which will tie the UK to Europe’s customs arrangements until a long-term trade deal can be agreed. The EU has insisted the backstop is vital to avoiding a hard border on the island of Ireland.