"Thug": Javier Milei insults Pedro Sanchez during his visit to Madrid

The two leaders clashed last year when Mr. Milei suggested that Mr. Sanchez's wife was corrupt, leading Madrid to recall its ambassador from Buenos Aires.

Mr. Milei spoke Sunday evening at the Madrid Economic Forum, a pro-libertarian gathering. As rock music played and some attendees shouted insults at Mr. Sánchez, Mr. Milei gestured forcefully and attacked the Spanish leader.

"If you also want to bully the local thug, I have no problem with that," Mr. Milei said, referring to Mr. Sánchez. Later, in a speech focused on defending his economic policies, Mr. Milei responded to audience members shouting "We need you here!": "Know that I will always be at your side when it comes to opposing the socialists."

The comments come hours after tens of thousands of people gathered in Madrid in a protest organized by opposition parties, accusing Mr. Sanchez's government of corruption.

Mr. Sanchez's wife, his brother, and a former senior aide are under investigation in separate corruption cases. Mr. Sanchez has dismissed the probes as part of a right-wing "smear campaign" aimed at bringing down his government.