Argentina's president-elect Alberto Fernandez has vowed to "turn the page" on the IMF-backed policies of incumbent Mauricio Macri, after voters weary of rising poverty and inflation swept the left back to power in Latin America' third biggest economy.

Argentina's electorate voted overwhelmingly on Sunday to ditch the economic liberalisation and austerity of Mr Macri, which has left the commodities-rich nation teetering on the brink of a $100 billion debt restructuring, and turned instead towards the Peronist left.

The two leaders have held brief talks about a transition of power, with Mr Fernandez vowing to take the country of over 44 million people in a vastly new direction to the business-friendly reform agenda espoused by his predecessor, a staid former magnate with close ties with the United States.

"We began to turn the page today. This page (of Macri) will be forgotten and we will start writing another story on December 10 when we arrive with Cristina in government," Mr Fernandez saidafter his election win, referring to his divisive running mate Cristina Fernandez de Kirchner.

The return of the Peronists, and populist ex-president Ms Fernandez de Kirchner, has startled some in Argentina and beyond, concerned that reforms to open Argentina more to global markets could be undone.

Markets today were mixed, still uncertain how to respond to the result with many questions unclear.

Argentina's central bank moved swiftly in the early hours to tighten capital controls during the transition and the peso closed 0.65% stronger.

In the parallel black market, the local currency was more volatile, having fallen as low as 77 to the dollar, while Argentine over-the-counter bonds dipped 1.6% on average.

How Mr Macri and Mr Fernandez work together over the next few weeks will be key. With talks looming with creditors over $100bn in debts, reserves are dwindling, inflation is sky-high and rising poverty is sparking anger.

Markets are watching closely to see where Mr Fernandez, a dark horse candidate who was a relative unknown until earlier this year, stands on key policies that could impact the peso, which crashed in August after he secured a landslide win in a primary vote.

In a bid to soothe markets, Mr Fernandez and Mr Macri signaled with their meeting that they would work together during the transition until the new government takes over in December.

Treasury Minister Hernan Lacunza told reporters the two leaders had shared a "good dialogue" and there would more meetings between the two teams in coming days.

"(There is) total willingness from this outgoing government to work together in the transition," he said.

Mr Macri later said in a tweet that he and his team would be available to work with Mr Fernandez to ensure a "democratic transition".

Mr Fernandez's victory shifts the political balance in Latin America, with two of the region's top three economies - Mexico and Argentina - now helmed by leftist leaders, even as right-wing governments in Chile and Ecuador come under pressure to roll back market reforms.

In the wake of his win, Mr Fernandez signaled that he would pursue close ties with leftist leaders in Mexico and Bolivia.

The election of Mr Fernandez, who Brazil's right-wing President Jair Bolsonaro has called a "red bandit," sets the stage for a run-in between South America's two biggest economies that could derail their Mercosur trade bloc.