Argentina's recently inaugurated far-right president has pledged to implement economic "shock treatment" in his inaugural address, emphasizing the country's financial constraints and recommitting to a rigorous austerity agenda.

Javier Milei, who secured an unexpected election triumph in November with radical promises to revamp the struggling South American economy, delivered his speech in Buenos Aires on Sunday amidst a day of elaborate ceremonies.

The 53-year-old, marking his remarkable ascent to power, made it clear that his economic approach would diverge significantly from those of his predecessors.

He outlined plans for substantial spending cuts aimed at reducing massive public debts and addressing inflation rates surpassing 140%.

Despite acknowledging short-term challenges, Mr. Milei expressed confidence that the long-term outcome would bear the fruits of their efforts.

His rapid rise to the presidency was fueled by a right-wing agenda that includes tightening restrictions on abortion rights and liberalizing gun laws.

During the campaign he said he would replace Argentina's currency with the dollar and abolish the country's central bank, along with a host of government departments.

Mr Milei waved to supporters during a procession to the presidential palace alongside his sister Karina, the confidant who is expected to play an influential role behind the scenes in his new administration.

He addressed the crowd for a second time from a balcony and chanted campaign slogans.

Mr Milei was presented with the blue and white presidential sash and baton, which he had personalised with engravings of his five dogs.

Among the guests was Ukrainian President Volodymyr Zelensky, who has met several Latin American leaders as he seeks to shore up global support for his country's war effort.

The pair were pictured embracing and Mr Zelensky later told reporters they had discussed ways Argentina could support Ukraine.

Noted