Veteran Congo President Denis Sassou Nguesso appeared on course for a fourth term on Monday after elections overshadowed by the sudden death of his main rival, Guy-Brice Parfait Kolelas, who passed away from coronavirus on polling day.
Provisional official results from 35 polling stations indicated that Sassou Nguesso, 77, was on track for a landslide first-round victory.
In the Poto-Poto district of the capital Brazzaville, for instance, he had picked up 89.15 percent of the vote, according to figures issued by the electoral commission.
"Across the country, the results are mostly in line with this trend," commission chief Henri Bouka said.
One of the world's longest-serving rulers, Sassou Nguesso was frontrunner in an election boycotted by the main opposition and under an internet blackout.
In power for a total of 36 years, he has long been accused by critics of iron-fisted rule and turning a blind eye to corruption, poverty and inequality despite abundant oil wealth.
Kolelas, 61, his only significant challenger, died on Sunday aboard a medical plane that took him to Paris, his campaign director Christian Cyr Rodrigue Mayanda told AFP.
A close friend of Kolelas told AFP that he had died five minutes after the plane touched down at Le Bourget airport north of Paris.
Kolelas had initially feared he had malaria, and discovered too late that it was coronavirus, the source said.
Unable to host his closing campaign rally in the capital Brazzaville, he posted a video from his sickbed, declaring he was "battling against death".
"Rise up as one person... I'm fighting on my deathbed, you too fight for your change," he urged his supporters, saying the election was "about the future of your children".
A Paris court said a criminal probe had been opened into the cause of death.
- Rose to power in 1979 -
Sassou Nguesso, a former paratrooper, first rose to power in the Republic of Congo in 1979.
He was forced to introduce multi-party elections in 1991 and was defeated at the ballot box a year later.
But he returned to power in 1997 following a prolonged civil war and has won every election since then, in conditions that the opposition says were fraudulent.
A constitutional amendment in 2015, which ended a ban on presidential candidates aged over 70 and scrapped a two-term limit, allowed him to run again in 2016. Two candidates in that vote -- former army general Jean-Marie Michel Mokoko and ex-minister Andre Okombi Salissa -- were sentenced in 2018 to 20 years in prison for "undermining state security".
Kolelas was the only major contender this time around after Congo's largest opposition group, the Pan-African Union for Social Democracy (UPADS), announced a boycott and other candidacies were withdrawn or excluded.
He came second in the presidential election of 2016, picking up 15 percent of the vote against 60 percent for Sassou Nguessou, according to official results.
Speaking after he cast his ballot, Sassou Nguesso said the "atmosphere of peace" during the election campaign was "a good sign for our democracy".
But when asked about security when election results are announced -- a moment that triggered a wave of violence at the last vote in 2016 -- he responded: "I'm not God".
Full results are likely to be announced on Tuesday or Wednesday, according to the electoral commission.
Flanked by its giant neighbour the Democratic Republic of Congo, the former French colony, also known as Congo-Brazzaville, has suffered a succession of coups, attempted putsches and insurrections since independence in 1960.
It has large reserves of oil, its major source of revenue, but its economy is in a slump, hurt by a collapse in crude prices, long-standing debt as well as the impact of the Covid-19 pandemic.