Buenos Aires, Dec 11 (IANS): Javier Milei, a far-right populist outsider, has been sworn in as the new President of Argentina in a ceremony held at the National Congress in Buenos Aires.

At the ceremony on Sunday, outgoing head of state Alberto Fernandez placed the presidential sash and handed the baton of command to Milei, whose term will last for four years, until December 10, 2027, reports Xinhua news agency.

Victoria Villarruel was sworn in as vice president.

In his address to the public following the inauguration, Milei noted that he had no alternative to a sharp, painful fiscal shock to fix the country's worst economic crisis in decades, with inflation heading towards 200 per cent.

"The bottom line is that there is no alternative to austerity and there is no alternative to shock treatment. We know that in the short term the situation will worsen.

"But then we will see the fruits of our efforts," the BBC quoted the the 53-year-old, who won a surprise election victory in November with radical pledges to overhaul the South American nation's ailing economy, as saying.

In recent years, Milei rose rapidly from relative obscurity to Argentina's highest office on a right-wing platform which includes restricting abortion rights, liberalising gun laws and climate change denial.

On his campaign trail, he said he would replace Argentina's currency (peso) with the dollar and abolish the country's central bank, as well as a series of government departments.

According to data from the International Monetary Fund (IMF), the peso is in long-term freefall, while poverty levels in Argentina have soared to 40 per cent and the economy is currently in deep recession.

Among the guests at Milei's swearing-in ceremony was Ukrainian President Volodymyr Zelensky.

Zelensky later told reporters they had discussed ways Argentina could support Ukraine.

Hungary's President Viktor Orban was also in attendance.