Chavez first called former Spanish Prime Minister Jose Maria Aznar Lopez a "fascist" and then repeatedly tried to interrupt current Prime Minister Jose Luis Rodriguez Zapatero, who was seated next to the king, Mercopress reported.
"Why don't you shut up?" Juan Carlos snapped at the leftist leader.
As Chavez continued to impose himself, Zapatero said to him: "I believe there is an essential principle to having a dialogue. And that's to be respectful if you want to be respected. We shouldn't resort to insults."
At that point, the summit's host, Chilean President Michelle Bachelet, intervened. She told participants, seated around the horseshoe-shaped table at Santiago's convention center, that everyone would have a chance to speak.