Ballot counting was under way in Benin on Monday after an election with little suspense as President Patrice Talon looked set to win a second term following a tense campaign.

The vote itself was largely peaceful in the West African nation once praised as a vibrant democracy, but critics have accused Talon of rigging Sunday's ballot by sidelining opposition leaders.

The cotton tycoon first elected in 2016 faced just two other rivals, little-known Alassane Soumanou and Corentin Kohoue, as most opposition figures were either disqualified by electoral reforms or were in exile.

In the economic capital Cotonou, residents went about their daily lives Monday morning, with little doubt over the election results scheduled to be announced by late Tuesday.

"We are relieved because the vote was peaceful, there was no violence like we had during the campaign. We were afraid, but in the end, everything went well," said one 64-year-old voter who asked to be identified only as Guy.

"Now we are waiting for results, even though there is no doubt that President Talon will get re-elected."

"Most likely, we will have a KO victory (first-round win)," said another voter, Marc Adrien Sedjame, who was "preparing to celebrate".

Opposition leaders had called for a boycott, urging supporters not to accept the election they say is fixed -- a claim Talon's backers deny.

"At most polling stations, the vote was calm and peaceful," Emmanuel Tiando, president of the country's electoral commission CENA, said Sunday evening.

"There were no major incidents," Tiando said, while noting that voting could not take place in 16 of the country's 546 boroughs.

Those included several opposition strongholds, in the centre and north of the country, where two protesters were killed and five were injured days ahead of the vote, after troops fired tear gas and live rounds in the air to break up a demonstration.

Protesters had blocked roads to the north last week, causing delays in the dispatch of electoral material.

The turnout is not yet known but is expected to be low. At several polling stations in Cotonou, an AFP journalist observed that participation did not exceed 30 percent.

The electoral commission said it had already received ballots from 400 boroughs.

An association of civil society groups, who deployed more than 1,400 election observers, said in its preliminary statement Sunday that "attempts to pressurize, intimidate, threaten, corrupt or harass voters were observed across the entire country."

The government however said it was "satisfied" with the vote, in which more than 4.9 million people were eligible to participate.