It is claimed the couple were found locked in a cubicle at the Lex Building in Brussels while continental leaders were thrashing out the UK’s future in the organisation.
The elicit encounter apparently took place on Thursday night with rumours circulating around the Belgian capital yesterday that those involved were from Germany.
According to The Sun, a source at the summit said Slovenian officials discovered the pair in the throes of passion.
The source said: Everybody is asking each other, ‘Do you know who it is’? I guess they just fancied a bit of How’s your Fatherland. But Chancellor Angela Merkel will not be happy if she finds out who they are.
‘At least someone enjoyed themselves because you could tell the leaders weren’t.’
The Lex Building is next door to where the crunch talks were taking place and is used by interpreters and translators.
It comes as Prime Minister David Cameron said he had secured ‘special status’ for the UK in the EU with his deal that was concluded after 30 hours of negotiations.