A leftist nationalist who is friendly with Venezuela's anti-U.S. president trounced a Bible-toting banana tycoon in Ecuador's presidential runoff on Sunday, partial results suggest.

A victory by Rafael Correa would strengthen South America's tilt to the left, with Ecuador joining like-minded governments in Venezuela, Bolivia and several other countries.

"We receive this very high honour that the Ecuadorean people have bestowed on us with profound serenity, with profound hope," Correa, 43, told a news conference.

His opponent, Alvaro Noboa, declined to concede defeat and demanded a recount, saying he was concerned about fraud.

With 31 per cent of the ballots counted, Correa had nearly 67 per cent of the vote, compared with 33 per cent for Noboa, Ecuador's Supreme Electoral Tribunal said before dawn Monday.

The results were consistent with an unofficial quick count by the citizens' election watchdog group and two exit polls.

Correa, an outspoken admirer of Venezuelan President Hugo Chavez, secured a place in Sunday's runoff by pledging a "citizens' revolution" to radically reform the country's political system. Correa, a U.S.-trained economist, has worried Wall Street by threatening to reduce foreign debt payments and oppose free trade efforts.

Three presidents driven from power

Ecuadoreans have driven the last three elected presidents from power, and Correa appealed to voters as a fresh face in a field of established politicians.

In the first round, Correa called U.S President George W. Bush "dimwitted" and threatened to reduce debt payments to free up money for social programs. He was favoured to win the first round but came in second to Noboa in the field of 13.

Correa's support climbed in the second round when he softened his radical rhetoric and made populist promises of his own.

Noboa, a 56-year-old billionaire who has touted his relationships with America's rich and powerful, said he would not concede defeat until the official count has been completed.

Noboa had run a populist campaign, crisscrossing Ecuador and handing out computers, medicine and money. Before voting on Sunday in the coastal city of Guayaquil, he read a passage from the Bible in the midst of a mob of supporters pushing to touch him.

The winner will face the tough task of ruling this poor, politically unstable nation which has had eight presidents since 1996, including three who were driven from office by street protests.

Ecuador is an oil-exporting country with strong agricultural and fishing industries, but three-quarters of its 13.4 million inhabitants live in poverty.