Senegalese parliament on Thursday passed a law setting a higher bar for presidential candidates after protests that saw police fire tear gas on demonstrators, with dozens arrested according to the main opposition party.
The change to the electoral law, approved by 120 of the body's 165 lawmakers with the election less than a year away, increases the number of signatures candidates must collect in order to stand for president.
The vote followed six hours of raucous debate during which a brawl erupted between MPs and one lawmaker tore up a copy of the legislation, which requires presidential hopefuls to collect the signatures of at least 0.8% of the electorate.
Some 52 000 signatures would have to be gathered in at least seven of the West African country's 14 regions, with a minimum of 2 000 in each.
The authorities say they fear an inflation in the number of presidential candidates in a country with nearly 300 parties, recalling the 47 lists that contested legislative elections in July 2017.
"No democracy can hold a presidential election without screening," Justice Minister Ismaila Madior Fall said, calling the bill a move to "clean up democracy" in Senegal.
But the opposition coalition blasted what they called a "constitutional coup d'etat", saying: "The sole aim of this is evident to everybody: to prevent opposition candidates from contesting."
Protests were held in several cities across the former French colony.
Former premier Idrissa Seck was among those arrested in the capital Dakar as well as opposition figures Malick Gakou of the Grand Parti and Thierno Bocoum of the Agir movement, their parties said.
Kilifa, a popular rapper and political activist, was also detained.
Around 100 demonstrators who had barricaded a street near parliament were dispersed by tear gas, AFP journalists reported.
Police also fired tear gas at around 50 protestors who were throwing stones at a police vehicle.
Faye said 12 people were arrested in the northern town of Saint-Louis, and the towns of Thies in the west and Mbacke in the centre together saw another 12 arrests or more.
The unrest came as President Macky Sall, who was elected in 2012 and is expected to run for and win re-election in February 2019, was set to meet his French counterpart Emmanuel Macron in Paris on Friday.
The first round of the presidential election in Senegal, often seen as a regional beacon of democracy, is scheduled for February 24.
Another proposed modification to the electoral law, to be debated in the coming weeks, would bar candidates with a criminal record.
This would apply to former minister and PDS presidential hopeful Karim Wade, son of Sall's predecessor Abdoulaye Wade. The younger Wade was convicted of "illicit enrichment" and sentenced to six years in jail in March 2015.
Sall pardoned him in June 2016 and he currently lives overseas.
Rights monitor Amnesty International earlier urged Senegal to "respect the right of people to demonstrate peacefully and to air their opinions against a backdrop of repression."