Senegal's Supreme Court has rejected opposition leader Ousmane Sonko's appeal against a libel conviction, potentially ruling him out of next month's presidential election.

He is seen as a strong potential challenger in the race to succeed President Macky Sall, who is stepping down after two terms.

Sonko has faced several court cases since 2021, all of which he denies.

Last month, a court ordered his reinstatement on the electoral roll.

This had been seen as potentially paving the way for him to contest the poll after he had previously been barred following a conviction in a different case.

In May last year, the Court of Appeal sentenced Sonko to six months in prison for defaming Minister of Tourism Mame Mbaye Niang.

After about 12 hours of hearing, the Supreme Court early on Friday rejected Sonko's appeal against the libel conviction.

According to electoral regulations, the conviction disqualifies Sonko in the 25 February presidential race.

However, Sonko's legal team said the legal setback was not final.

"The fight will continue," his lawyer Ciré Clédor Ly told reporters outside the court in the capital, Dakar.

His repeated arrests over the past two years have sparked several bouts of deadly unrest in one of West Africa's most stable democracies.

Reports say there was no immediate sign of public protest in response to Friday's ruling.

The Constitutional Council is set to publish a final list of cleared presidential candidates on 20 January.