Reports of angry exchanges between the Prime Minister and Brussels chief, leaked to a German newspaper, caused a huge fallout on either side of the channel.
But today, Mr Juncker insisted he was not responsible for the scathing account of his meeting with Theresa May.
But the briefing, which took place at 10 Downing Street last month, sparked a furious reaction from the British Prime Minister – who subsequently accused the EU of trying to interfere in the General Election and “run over us” in Brexit talks.
And she accused European politicians and officials of plotting to “deliberately affect” the result of next month’s poll by issuing “threats” against Britain.
She said: “During the Conservative Party leadership campaign, I was described by one of my colleagues as a bloody difficult woman.
“And I said at the time the next person to find that out will be Jean-Claude Juncker.”
In Europe too, the leaked information was met with a serious backlash.
While Donald Tusk, the President of the European Council, called for more “discretion” over private talks.
The meeting was attended only by the EU chief and his Chief of Cabinet Martin Selmayr, along with Mrs May and one of her advisors.
It has now been rumoured that Mr Selmayr passed on that information, but this has not been confirmed.