The relationship between the EU and newly-elected US President Donald Trump has got off to an inauspicious start, after the President of the European Commission Jean-Claude Juncker fired a volley of criticism across the Atlantic.

"We will need to teach the president-elect what Europe is and how it works,” Juncker, arguably the EU’s most powerful politician, told students during a conference in Luxembourg, his home state. “I think we will waste two years before Mr. Trump tours the world he does not know."

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"The election of Trump poses the risk of upsetting intercontinental relations in their foundation and in their structure," said Juncker, and said that his attitude towards joint security obligations was “pernicious.”

During his campaign Trump has accused European leader of shirking their financial commitments to NATO, and said that unless they were adhered to, Washington may no longer protect its allies in case of attack. Trump has also criticized the proposed TTIP treaty between the EU and the US, and has previously dismissed climate change as a “Chinese hoax.”

"We would like to know how things will proceed with global trade policy," Juncker said in Berlin on Thursday. "We would like to know what intentions he has regarding NATO. We must know what climate policies he intends to pursue. This must be cleared up in the next few months."

READ MORE: EU Commission president wants clarity from Trump on NATO, trade

Perhaps in the most revealing detail of the EU’s reaction to Trump’s election, Juncker has admitted that he was forced to tear up a congratulatory speech addressed to the winner of Tuesday’s vote, after discovering that the only version of the document spent pages congratulating America on electing its first female President.