Jean- Claude Juncker raged against the public member after he was forced to interrupt his speech because of laughter in the room.
Speaking in Brussels, he was discussing the proposals for reform he presented during his annual State of the Union address last week.
He said: “I’m not in favour of any large institutional reform (…) You! Don’t laugh! You two!”
“I was speaking to Philippe. Just for those who didn’t see where I was looking, what direction my eyes were looking at. It was Philippe de Buck whom I’ve been looking at for a long time.”
Mr de Buck is the director general of BUSINESSEUROPE, an international organisation representing 40 leading industries and employers federations.
Earlier in the live session, Mr Juncker rudely interrupted the debate when his phone went off to the amusement of his Brussels colleagues.
Mr Juncker suffered a similarly embarrassing moment when his phone went off during a joint press conference with Slovak Prime Minister Robert Fico and Commission vice-president Maros Sefcovic, the European commissioner from Slovakia.
This time, after saying he was a fan of the Good Friday Agreement, which he described a “major achievement” for the Irish, British and EU, his ringtone was picked up on the microphone.
Before answering it during the ‘State of the Union’ European Economic and Social Committee session, he said “that’s my wife” as he had once done before.
Mr Juncker‘s disrespect for the audience falls in line with the criticism moved against him by anti and pro-EU politicians alike.
Remainer Lib-Dem leader Sir Vince Cable recently blasted the EU boss, calling him “pompous.”
Sir Vince said: “Juncker embodies many of the EU‘s failings. He is pompous, self-important and overpaid.”