Jean-Claude Juncker says leaking details of 'disastrous dinner' with Theresa May was a 'serious mistake'

But EU Commission president denies he was behind the leak

Jean-Claude Juncker described Theresa May as a 'tough lady' (Getty Images)

It was a “serious mistake” to leak details of his private dinner with Theresa May, Jean-Claude Juncker has admitted, but the EU Commission president has denied he was behind the information getting out.

A diplomatic row erupted earlier this month after German newspaper Frankfurter Allgemeine Zeitung (FAZ) was given detailed information about the nature of the discussions.

It reported that EU officials and Mr Juncker were surprised that Ms May did not appear to be fully briefed for the meeting and claimed she had unrealistic expectations about the length and process of negotiations.

The Prime Minister was said to have refused to accept that the UK owed the EU billions of euros, saying there was no such demand in EU treaties. She was told in response that the EU was “not a golf club”.

The morning after the meeting, Mr Juncker called German Chancellor Angela Merkel and reportedly said Ms May “lived in another galaxy” and was “deluding herself”.

It prompted Ms Merkel to quickly amend a passage in her speech to the EU’s Brexit summit, a speech that would be described as her toughest yet.

“I have to put it in such clear terms because unfortunately I have the feeling that some in Britain still have illusions,” she said.

“But that would be a waste of time.”

Mr Juncker said he regretted the fact that the nature of the conversation had been made public.

“Regardless of the relationship between the participants at this dinner, the fact that this conversation was reported is a serious mistake,” he told German newspaper Handelsblatt.

He also denied he was the source of the leak.

“I get along fine with May,” he added. “She’s a tough lady.”

The dinner was reportedly attended only by Ms May, one of her advisers, Mr Juncker and his cabinet chief Martin Selmayr. Some commentators have accused Mr Selmayr of being the source of the leak.

The publication of parts of the conversation led Ms May to accuse EU leaders of trying to directly influence the result of the UK general election.

“Britain’s negotiating position in Europe has been misrepresented in the continental press”, said the Prime Minister at the time.

"The European Commission’s negotiating stance has hardened. Threats against Britain have been issued by European politicians and officials. All of these acts have been deliberately timed to affect the result of the general election.”

She dismissed the leak as “Brussels gossip”.