Quito, Apr 12 (IANS): Former banker and three-time presidential candidate Guillermo Lasso declared victory in Ecuador's presidential run-off elections, calling it a historic day for the South American country.

"This is a historic day. It is a day in which all Ecuadorians have decided their future. They have expressed with their vote the need for change and the desire for better days for all," Lasso said on Sunday after the National Electoral Council (CNE) released preliminary official results.

With 97.71 per cent of the ballots counted, Lasso had 52.51 per cent of the votes while his left-leaning rival Andres Arauz obtained 47.49 per cent, reports Xinhua news agency.

In his victory speech, Lasso thanked Ecuadorians for their support of his candidacy, which was backed by an alliance between the Creating Opportunities (CREO) movement, which he leads, and the Social Christian Party (PSC).

"Thank you from the bottom of my soul for giving me the opportunity to be your president and to be able to serve you," Lasso said as he was surrounded by supporters chanting "Lasso, president".

The 65-year-old politician and businessman said he would take on the challenge of changing the future of the country with responsibility and "achieving opportunities for all of Ecuador".

"We will work tirelessly to fulfill our commitments to you," said Lasso, who reiterated his desire to build a "free and prosperous country".

Arauz promptly conceded defeat to Lasso and vowed to continue his political endeavour.

"This is an electoral setback, but in no way is it a political or moral defeat, because ours is a lifelong project.

"It is a struggle on the path of organising and building a more just and supportive future for all Ecuadorians," he said.