Argentina's Peronists swept back into power on Sunday, ousting conservative president Mauricio Macri in an election result that shifts Latin America's No. 3 economy firmly back toward the left after it was battered by economic crisis.

Peronist Alberto Fernandez had 47.79% of the vote, ahead of Macri's 40.71%, with more than 90% of ballots counted, putting the center-left challenger over the 45% threshold to avoid a runoff and win the election outright.

Mr Macri, speaking at his election party, conceded the race and congratulated Fernandez. He said he had invited Mr Fernandez to the presidential palace on Monday to discuss an orderly transition, seen as essential for Argentina's shaky economy and markets.

Mr Fernandez, speaking afterwards alongside running mate Cristina Fernandez de Kirchner, said he would meet Mr Macri and collaborate with the outgoing leader "in any way we can".

"The times ahead are not easy," he told cheering supporters at his election party. "But of course we will collaborate in everything we can, because the only thing that concerns us is that Argentines stop suffering once and for all."