Il Nuovo Postiglione - Argentina's Milei sings hard rock at book launch

"I wanted to do this because I wanted to sing," Milei told spectators, before performing his own version of a local rock song at the Luna Park stadium, which has hosted major sporting events and concerts by international stars.

Then, in another twist, he launched into a lengthy lecture from his 13th book "Capitalism, Socialism and the Neoclassical Trap."

Milei returned to some of his favorite themes which he has brought up in international fora, such as slamming socialism and abortion, which he said was a "mechanism to massacre populations."

The 53-year-old libertarian was a political outsider when he was elected last year on a wave of anti-government sentiment, vowing to halt Argentina's decades of economic decline.

The concert saw the return of his rock-star persona, a remnant of his youth playing in a Rolling Stones cover band, which won voters over during his election campaign.

"I am here to support Javier in everything he does. I like his ideas, I like what he does, he is sincere, he is transparent, he says what he thinks," Santiago Roldan, a 20-year-old supermarket employee, told AFP.

Milei, an economist who became a popular television panelist before entering politics, gave a lesson in liberal economics stretching from ancient Egypt to the fall of the Berlin Wall.

As the evening dragged on, many of the around 10,000 supporters, left.

Milei "remains a character who likes to put on a show," said political scientist Rosendo Fraga of the Academy of Moral and Political Sciences.

The firebrand president has been in the international spotlight in recent days after he called Spanish Prime Minister Pedro Sanchez's wife "corrupt", sparking a diplomatic spat.

The show came just hours after the release of the latest statistics showing economic activity had slowed 8.4 percent year-on-year in March, amid his government's austerity drive.

He also devalued the peso by 50 percent, and the measures have hit consumers hard. While inflation is slowing, prices are still up some 290 percent from the previous year.

E.Spicuzza--INP