The 52-year-old actor, who has vigorously campaigned for the democratic leader in US elections and considers Obama a "long-time friend", abruptly stormed off while dining with billionaire hotel and casino owner Steve Wynn in Las Vegas earlier this month after the magnate branded the US leader an "a**hole".

In a statement issued through his publicist, George told the Las Vegas Review-Journal: "He called the president an a**hole, that is a fact. I said the president was my long-time friend and then he said, 'Your friend is an a**hole.'

"At that point I told Steve that he was an a**hole and I wasn't going to sit at his table while he was being such a jackass."

However, it seems the pair have differing accounts of the incident as Steve claims 'The Monuments Men' star "got drunk" on premium vodka and threw a "hissy fit" when a fellow diner at their table made a joke about former Soviet Union president Mikhail Gorbachev.

Steve added: "Clooney's fun to be with when he's sober. If you have a chance to drink with him, you want to get there early, and don't stay late."

According to eyewitnesses, the tense scene nearly became violent as Steve's bodyguards quickly appeared in the midst of the argument after George pointed a finger at the entrepreneur.

An insider told the New York Post newspaper: "Wynn's three goon-like bodyguards immediately loomed up behind Rande [Gerber, George's business partner] and George. Before Wynn's bodyguards could touch them, George and Rande got up and walked out."