Javier Milei sworn in as Argentina's president

"I swear to God and country... to carry out with loyalty and patriotism the position of president of the Argentine nation," he said.

Libertarian economist Javier Milei was sworn in Sunday as Argentina's president, after a resounding election victory fueled by fury over the country's economic crisis.

Argentina's new president Javier Milei delivers a speech after swearing in during his inauguration ceremony. (AFP)

"I swear to God and country... to carry out with loyalty and patriotism the position of president of the Argentine nation," he said as he took the oath of office, before outgoing President Alberto Fernandez placed the presidental sash over his shoulders.

Javier Milei warned there was no alternative to a fiscal "shock" in his maiden speech after being sworn into office on Sunday, saying his predecessors had left the country without funds and on a path to hyperinflation.

The outsider libertarian, a former TV pundit, has ridden a wave of voter anger at triple-digit inflation, tumbling foreign currency reserves and rising poverty amid the South American country's worst economic crisis in over two decades.

"We need a fiscal adjustment that falls on the state and not on the private sector," he said. "There is no money."