Prime Ministers must stop listening so much to their voters and instead act as “full time Europeans”, according to Jean-Claude Juncker.

Elected leaders are making life “difficult” because they spend too much time thinking about what they can get out of EU and kowtowing to public opinion, rather than working on “historic” projects such as the Euro, he said.

The president of the European Commission ridiculed British leaders for acting on "national reflexes" and telling voters they had successfully defended the country's national interest in post-summit press conferences, rather than "speaking over Europe in the proper way".

He said: “I remember the highly exciting period when we were preparing the Maastricht treaty, and step by step we were moving in the direction of the single currency… It was a shared sentiment of foreign ministers and Prime Ministers that we were in charge of a big piece of history. This has totally gone.”

“We have full time Europeans when it comes to taking, and we have part-time Europeans when it comes to giving,” said Mr Juncker, a former prime minister of Luxembourg who has spent more than 30 years around the EU institutions.

“Too many politicians are listening exclusively to their national opinion. And if you are listening to your national opinion you are not developing what should be a common European sense and a feeling of the need to put together efforts. We have too many part-time Europeans.”