BUENOS AIRES (AFP) - Leftist contender Daniel Scioli conceded defeat to pro-market leader Mauricio Macri in Argentina's presidential run-off on Sunday (Nov 22), ending 12 years of rule by the populist Peronist movement.

"By popular will, a new president has been elected: Mauricio Macri," Mr Scioli told supporters at a rally in Buenos Aires.

Official results showed Mr Macri with just under 53 per cent of the vote to 47 per cent for Scioli, with more than 75 per cent of votes counted.

The economically liberal, socially conservative Macri seized the momentum after forcing a run-off when he finished close behind Mr Scioli in the first-round vote last month.

"We made an effort and had the will to convince. I am a democrat and I respect the popular will, which has chosen an alternative," Mr Scioli said.

He said he hoped that "God enlightens (Macri) to improve on the progress the country has made" under Ms Cristina Kirchner, the outgoing leftist-populist president.

Mr Scioli had vowed to defend Argentine salaries and industry in the face of Mr Macri's proposed economic reforms.

Mr Macri has vowed to liberalise the economy and ease restrictions on US dollar transactions and imports.