Speaking at the Alpbach Media Academy this morning, Mr Juncker said: ‘Borders are the worst invention ever made by politicians.’

The contentious remarks from the Brussels chief are the polar opposite of moves by elected leaders of EU member states who have tighten their borders over recent months after more than a million entered the bloc from Syria in less than a year.

Mr Juncker also said a stronger EU was the best way of beating the rising trend of nationalism cross Europe.

In another extraordinary remark, he appeared to warn of war on the continent if the EU disintegrates as he echoed the warning from the former French president Francois Mitterrand, who said nationalism added to nationalism would end in war.

‘This is still true so we have to fight against nationalism,’ Mr Juncker said.