Opposition supporters again clashed with security forces in the Senegalese capital Dakar on Tuesday night ahead of Sunday’s election.
Police fired tear gas at demonstrators; at least six people have been killed in election-related violence in recent days.
There is widespread anger over President Abdoulaye Wade’s decision to run for a third term at the age of 85.
His rivals say his candidacy is illegal because it breaches a two-term limit.
The west African state has enjoyed decades of democracy, but the violence is now overshadowing the election.
The singer and opposition leader Youssou N’Dour who’s been banned by a court from running was slightly injured in the leg by a projectile as protests degenerated.
He had defied a police ban on demonstrations to lead a protest.
EU observers have criticised the ban. They have called for more transparency from the government, warning that hundreds of thousands of newly registered voters may be unable to cast their ballots because they haven’t collected their cards.