Alberto Fernandez at a polling station during the Primary, Open, Simultaneous and Mandatory elections (PASO), in Buenos Aires, Argentina, on 12 August 2019. Argentines vote for pre-candidates to be defined in the general elections of October 27.

The favorite to be the Argentina's next leader has claimed that a loan from the International Monetary Fund (IMF) cannot be paid back.

Argentine assets cratered last week after a shock primary poll indicated that a left-wing ticket of Alberto Fernandez and former President Cristina Fernandez de Kirchner will win elections in October and defeat current leader Mauricio Macri.

In particular, the bond and currency markets reflected investor unease at the move away from Macri's market-friendly policy agenda. Macri borrowed $57 billion from the IMF last year on the agreement he would implement austerity measures to trim the country's huge debt and make the repayments.

In a weekend article published by newspaper Clarin, Fernandez suggested that if he becomes leader, he would look to renegotiate the deal.

"I would say that there is only one incontrovertible reality and that is that Argentina in these conditions is not able to repay the debts it took on," he said.