Quito, Apr 13 (IANS): Ecuador's National Electoral Council (CNE) will take a few days to officially announce the winner of the presidential runoff due to procedural requirements, a top official said here

In a statement on Monday, President of the election body, Diana Atamaint, said preliminary results issued late Sunday by the CNE indicated an "irreversible" trend, Xinhua news agency reported.

But political parties "have the right" to file complaints and have them addressed before the definitive results are published, she added.

In addition, each of the 24 provincial electoral boards must review ballots that presented inconsistencies.

With 99 per cent of the ballots tabulated by noon on Monday, former banker Guillermo Lasso maintained his lead with 52.52 per cent of the valid votes (4,563,430), according to the CNE.

Meanwhile, his progressive rival Andres Arauz, a left-leaning economist endorsed by former President Rafael Correa, garnered 47.48 per cent of the votes (4,125,896).

Voter turnout in Sunday's elections was high, with 82.72 per cent of the country's more than 13 million eligible voters going to the polls, though protest votes in the form of null ballots accounted for 16.33 per cent.

Lasso's victory came as somewhat of a surprise since Arauz won the first round of the elections with a sizable lead over the ex-banker, albeit in a crowded field of candidates, and weeks before the runoff, several polls gave Arauz a minimum 7-point advantage.

However, more recent polls showed growing support for Lasso.