Pedro Castillo, a school teacher running for the Free Peru party, is leading the country's presidential elections with 16.1 per cent of the vote, according to the results of an exit poll published by local media.

Preliminary data also showed candidates, Hernando de Soto, of the Advance Country party, and Keiko Fujimori, of the Popular Force party, were at second place with 11.9 per cent of the votes each, reports Xinhua news agency.

If he maintains the lead, Castillo will face off against the runner-up, which will either be De Soto or Fujimori, in a run-off on June 6.

More than 25 million people were eligible to cast their ballots in Sunday's polls to elect the President, two Vice Presidents, 130 Congressmen, and five representatives to the Andean Parliament.

There were a total of 18 presidential candidates in the fray.

About 90,000 members of the national police and 62,000 members of the armed forces were deployed at polling stations across the country.