Senegalese opposition figure Ousmane Sonko slams a court ruling against him over a defamation case that might make him ineligible to run for president and describes it a "theatre play", calling on his supporters to protest the decision.

"What happened yesterday was a theatre play in which the roles were assigned," he said in a video address on Tuesday.

In March, the politician was sentenced to a two-month suspended sentence and a fine for defaming Tourism Minister Mame Mbaye Niang, while an appeals court on Monday increased the fine and extended his term to six months, threatening his plans to remain an eligible candidate for the presidential elections in 2024.

Read more: Senegal's president: Africa not breeding ground for new Cold War

"It in no way calls into question our plans," he said.

"I am now more than ever a candidate" for the February 2024 presidential election, he stressed. 

"Only God can prevent my candidacy... No human being can prevent it."

The opposition leader asked his supporters to "stay on your feet and mobilize."

"We have only one opponent, that of Senegal, (current President) Macky Sall," he said, calling them to turn up in large numbers in the Friday protests.

Read more: Turkish elections will decide the fate of the Syrian question: Report

The Friday protests were initially called for earlier by leading members of his coalition.

"The people have to mobilize to support Ousmane Sonko in this fight," Khalifa Sall, one of the Yewwi Askan Wi coalition leaders, told reporters.

The defamation case is not the only trial the opposition politician is up against.

Sonko, who came in third in the 2019 presidential elections against Sall, will also be facing an alleged rape and death threats trial later this month.

Read more: Kilicdaroglu calls on supporters to ensure victory in 1st voting round

He describes the trials as the government's attempts to sabotage his candidacy.

Denying the claims, Senegalese government spokesperson Abdou Karim Fofana said on Tuesday that "everyone is answerable before the law, whether an opponent, or in power, or a government minister."

Fofana added that the protests can take place with no reason to be banned "as long as there is no risk of disturbing the peace."

Political tensions in the African country have further increased after Sall refused to rule out rerunning for his third term, a move described by his opponents as unconstitutional.

Dethie Fall, another Yewwi Askan Wi coalition member, called for a demonstration on May 19 against a "campaign to liquidate Ousmane Sonko."

He said that not to take action "would be to let democracy be transformed into a monarchy and dictatorship by President Macky Sall, who has only one idea in mind, the third mandate."