The remarks are diplomatic dynamite at a time when relations between Washington and Brussels are already strained over Europe’s meagre contributions to NATO and the US leader’s open preference for dealing with national governments.

Speaking at the centre-right European People Party’s (EPP) annual conference in Malta this afternoon, the EU Commission boss did not hold back in his disdain for the White House chief’s eurosceptic views.

“If he goes on like that I am going to promote the independence of Ohio and Austin, Texas in the US.”

Mr Juncker’s comments did not appear to be made in jest and were delivered in a serious tone, although one journalist did report some “chuckles” in the audience and hinted the EU boss may have been joking. The remarks came in the middle of an angry speech in which the top eurocrat railed widely against critics of the EU Commission.

They will be seen as totally inexplicable at a time when EU-US relations appeared to be on the mend, with Vice-President Mike Pence having completed a largely successful trip to Brussels and the commander-in-chief himself significantly softening his tone towards the EU project.

Mr Juncker did not criticise Britain at all during his speech, and only made reference to Brexit in relation to Mr Trump and the opportunities it presents for Europe to reform itself.

Speaking before him, EU Council president Donald Tusk was less reserved in his remarks about the UK vote as he tore into the populist politics which led to Brexit.

The Polish eurocrat said the argument over sovereignty – epitomised by the Vote Leave slogan ‘take back control’ – was “a view that is both foolish and dangerous” and that the EU guaranteed countries’ strength of the world stage.

He also accused populist politicians, such as the Netherlands’ Geert Wilders and France’s Marine Le Pen, of promoting “organised hatred” with their views on immigration.

In a series of thinly veiled comments about immigration, a major political issue in his homeland and Malta, the Italian official said Europe should do more to defend its historic identity.He said: “We shouldn’t be ashamed of saying we’re Christian. We’re Christian, it is our history.

“If we leave our identity we will have in Europe all identities but not European identities. For this we need to strengthen our identity.

“It is impossible to win without identity, without our values. Of course we are different, many languages, many ideas, but we are united on the values and this is the most important content.”