Boris Johnson was accused of being an “unelected” Prime Minister who risks gambling with peace and stability in Northern Ireland by Dublin’s EU commissioner.

Agriculture Commissioner Phil Hogan stressed the UK must “honour its commitment” to the backstop – the measure aimed at preventing a hard border with Ireland which the Prime Minister wants to see removed from the Brexit divorce deal.

In a strongly-worded intervention, reported by the Irish Independent, Mr Hogan warned that a hard Brexit will create a “foul atmosphere” between the UK and the European Union.

In a pointed reference to Mr Johnson, who has written a biography of Winston Churchill, he said: “In the event of a no-deal Brexit, the UK government’s only Churchilian legacy will be ‘never have so few done so much damage to so many’.”

Mr Johnson’s claim that the backstop is anti-democratic “seems strange” as it is “coming from an unelected prime minister”, Mr Hogan is reported to have said.

In his speech in Carlingford, Mr Hogan is quoted as saying: “If the UK fails to prevent a crash-out Brexit they should be under no illusion regarding the foul atmosphere they will create with their EU partners and the serious consequences this will have for negotiating any future trade agreement.

“The UK continues to negotiate based on its experience of being an EU member.

“This misses the point completely: from the moment the UK came back to Brussels with the infamous red lines, the EU has negotiated on the basis of the UK opting for third country status.”

A hard Brexit would mean “pain for everyone, but the worst pain will be felt by the people of the UK”, he added.