European Commission President Jean-Claude Juncker warned Britain on Tuesday that voting to leave the EU would be "an act of self-harm". Juncker said such a decision would endanger everything Europeans had worked together to achieve.

He said, "History has taught us a simple lesson: Europe is stronger together. We are more powerful when we join our forces. We are more secure when we look out for each other. And we are more prosperous when we trade with each other."

"Leaving the European Union would put all this at risk. It would damage what we have achieved so far. And it would diminish what we can achieve tomorrow. To turn your backs on your neighbour and retreat into isolation would go against everything that Europe and the United Kingdom stand for. To leave would be an act of self-harm."