Mauricio Macri, presidential candidate of the Cambiemos (Let's Change) coalition, waves to his supporters after the presidential election in Buenos Aires, Argentina, November 22, 2015. Conservative opposition candidate Macri comfortably won Argentina's presidential election on Sunday after promising business-friendly reforms to spur investment in the struggling economy. [Photo/Agencies]

BUENOS AIRES - Conservative opposition candidate Mauricio Macri won Argentina's presidential election on Sunday after promising business-friendly reforms to spur investment in the struggling economy.

Macri's supporters swarmed to the Obelisk in the heart of Buenos Aires' theatre district for a giant street party as subdued ruling party candidate Daniel Scioli conceded defeat.

Argentina's election body said Macri had 52.1 percent of votes and Scioli had 47.9 percent with returns in from 91.5 percent of polling stations.

"This is the beginning of a new era that has to carry us toward the opportunities we need to grow and progress," Macri told supporters at his headquarters, which pulsed with Latin music and was festooned with white and sky-blue balloons, the colors of the Argentine flag.

In a sign of Argentines' weariness with a spluttering economy, rising crime and corruption, Macri had gone into the run-off election with a comfortable lead in opinion polls over Scioli, the candidate of outgoing President Cristina Fernandez.

During the campaign, Scioli warned that Macri's orthodox policies are similar to those that preceded Argentina's 2001-02 economic crisis, which tossed millions of people into poverty.

But with economic growth slowing sharply and inflation running at more than 20 percent, voters were keen for change.

Macri promises to set Latin America's third biggest economy on a more free-market course after a combined 12 years of leftist populism under Fernandez and her late husband and predecessor Nestor Kirchner.

Barred from seeking a third straight term, Fernandez will leave office with Argentina deeply divided between those who back her protectionist policies and defense of worker rights and others who blame her policies for weak economic growth.