Opposition figures reacted angrily on Tuesday after Ivory Coast's top court rejected 40 candidates for upcoming presidential elections, validating the contested bid of head of state Alassane Ouattara but sidelining his predecessor, Laurent Gbagbo.

Also barred was former rebel leader turned prime minister Guillaume Soro, 47, a onetime Ouattara ally who had been sentenced to 20 years in absentia over alleged embezzlement.

But on Tuesday the African Court on Human and Peoples' Rights called on the Ivorian authorities to allow Soro to contest the vote.

However, the court's provisional ruling is likely to have limited impact, as Ivory Coast withdrew its recognition of its jurisdiction in April.

Soro had late Monday lashed the Constitutional Council's rejection of his candidacy "politically motivated, legally flawed, and part of a process of crushing democracy and the state of law" .

Tensions in the West African state are running high ahead of the polls -- more than 3,000 people died in post-election violence in 2010-11.

Protests broke out in several cities, including in southeastern Bonoua, the hometown of Gbagbo's wife Simone,where some 300 mainly young people marched against Ouattara's candidacy in defiance of a ban on demonstrations.

Local residents said the protesters set up barricades on the motorway to neighbouring Ghana before police broke them up.

Anti-Ouattara demonstrations drawing hundreds of protesters were also staged in the main western cities of Guiglo, Bangolo, Facobly and Duekoue.

Simultaneously the Ivorian authorities announced that a ban on "marches and sit-ins" was prolonged to September 30.

- 'Spiral of exclusion' -

One of the four accepted candidates, former prime minister Pascal Affi Nguessan, said the country was "descending into a spiral of exclusion", a phenomenon he described as "the most consummate sign of the regime's tyrannical nature."

Nguessan, 67, served under Gbagbo and heads the party he founded, although he is struggling to win over loyalists who want the former president to be their flagbearer.

Gbagbo was forced out by Ouattara after a brief civil war following the elections in 2010 and was then prosecuted by the International Criminal Court (ICC) on charges of crimes against humanity.

He was released by the ICC in January 2019 and lives in Brussels pending the outcome of an appeal against the ruling.

But Gbagbo's application for the October 31 elections -- submitted in his name by followers -- was rejected by the Constitutional Council as he had been sentenced to a 20-year term in absentia last November over the looting of a regional bank during the post-election crisis.

"The Constitutional Council missed a historic chance to show its independence," Nguessan said in a statement.

He referred to a constitutional change in 2016 that enabled Ouattara to argue that the two-term limit on presidential tenure had been reset to zero -- a rationale accepted by the court.

"It accepted the candidacy of the outgoing president, who is clearly ineligible, and re