Demonstrators in Dakar burned tires and set fire to buses and a large supermarket, the latest in a series of outbreaks of violence that have shaken Senegal's reputation as a bastion of stable democracy, just months ahead of a presidential election.
Thursday's clashes began when Sonko supporters were blocked from accompanying his motorcade to the courthouse where he faces trial for libel.
Sonko is being tried for allegedly defaming a minister, a case that could determine whether he will be eligible to run in presidential elections next February.
Sonko's charges stem from alleged slander toward Tourism Minister Mame Mbaye Niang, a member of President Macky Sall's party, after accusing him of being criticized by state inspectors for his handling of a rural unemployment scheme.
He faces separate charges of allegedly raping a masseuse - a case that in March 2021 unleashed violence that claimed around a dozen lives.
The unrest has rattled Senegal, a country that has a reputation of being an oasis of stability in troubled West Africa.
Sonko's supporters say Sall is using the judiciary as a means to sideline him for the vote, a charge the president denies.
Sonko was taken from his home early Thursday under heavy police escort after being confined there on the eve of the trial as the authorities braced for protests.
On Tuesday, Sonko held an authorized rally where he urged thousands of supporters to come en-masse to back him on the day of the trial.
But there was no sign of any crowd in the area around his home, where armored vehicles, gendarmes and barricades were heavily deployed.
Riot police were also in place around the court house, and many schools in the capital were closed.
A firebrand speaker who came third in the 2019 presidential election, Sonko has enjoyed a rapid political ascent thanks in part to his popularity with young people.
He has already declared himself a candidate for the 2024 race, but his path to the presidency faces judicial hurdles.
Sonko has been accused of slander by Tourism Minister Mame Mbaye Niang, a member of Sall's party, after accusing him of being criticized by state inspectors for his handling of a rural unemployment scheme.
He faces separate charges of allegedly raping a masseuse -- a case that in March 2021 unleashed violence that claimed around a dozen lives.
The unrest has rattled Senegal, a country that has a reputation of being an oasis of stability in troubled West Africa.
In recent years, several other prominent opponents of Sall have had their political careers cut short by legal cases. Authorities have denied any misuse of state institutions.
Sonko has also claimed Sall intends to override the constitution and run for a third term.
Sall was elected in 2012 and again in 2019. He has neither confirmed nor denied whether he intends to seek a third mandate.
This report was sourced from Reuters and Agence France-Presse.