Sonko, President Macky Sall's fiercest critic, on Monday was charged with fomenting insurrection and his party dissolved, prompting clashes between protesters and police.
The leading opposition figure has faced a string of legal woes, which he claims have been designed to keep him out of politics and jeopardise his participation in the February 2024 presidential election.
The interior ministry said protests erupted Monday afternoon in the southern city of Ziguinchor where "two lifeless male bodies" were discovered. The ministry press release sent to AFP did got give further details of the circumstances of the deaths in the city where Sonko is mayor.
Less than two hours after Sonko's indictment, the interior minister announced that his PASTEF party would be dissolved for having "frequently" called for insurrection, leading to destruction and the loss of life.
The party slammed the move, saying in a statement that the country's stability was "now compromised," and that the dissolution was "anti-democratic."
Sonko's sentencing in June in absentia to two years in prison in a moral corruption case sparked clashes that left 16 dead according to the government, 24 according to Amnesty International, and 30 according to PASTEF.
He had not been jailed despite that conviction, which rendered him ineligible to stand in next year's election.
On Friday, he was arrested on new allegations tied to comments he has made, rallies he has held, and other episodes since 2021.
The new charges include undermining state security, criminal association with a terrorist body, disseminating false news and theft.
"It's a farce," Cire Cledor Ly, one of Sonko's lawyers, told reporters outside the courthouse on Monday. "It's a plot that was formed, thought out, planned and executed."
Sporadic clashes broke out on Monday evening in the suburbs of Dakar, AFP journalists saw. The demonstrators burned tires and set up roadblocks while chanting "Free Sonko," before being dispersed by police with tear gas.
Earlier on Monday, authorities announced they were restricting mobile internet access due to "hateful and subversive" messages on social media.
Amnesty International condemned the internet restrictions, calling them an "attack on freedom of information."
Sonko had called, a day earlier, on Senegalese people to "stand up" and "resist... oppression."
A former civil servant, Sonko rose to prominence in the 2019 presidential election, coming third. He has portrayed Sall as a would-be dictator, while the president's supporters say Sonko has sown instability.
Sall in early July eased tensions in the normally stable West African nation by announcing he would not seek a controversial third mandate, following months of ambiguity and speculation about his intentions.