Senegal riot police used teargas, truncheons, and a water cannon on Wednesday to disperse hundreds of people in the capital Dakar protesting at President Abdoulaye Wade's decision to seek a third term in office.
The clashes in the West African state erupted after demonstrators shouting "Wade step down" gathered at a downtown square near the presidential mansion, shrugging off a state ban on protests in the run-up to the February 26 vote.
"There have been lots of minor injuries," El Hadji Sarr, a doctor treating some of the wounded, told Reuters. He said some of the protesters had been burned by the water cannon, which sprayed heated water.
Cat-and-mouse battles continued between rock-throwing youths, some wearing bandanas against the teargas, and security forces on Dakar's back streets, Reuters witnesses said.
The octogenarian president has rejected pressure from his rivals and from international partners to withdraw from the race, which pits him against more than a dozen other hopefuls including former vice presidents Macky Sall and Idrissa Seck.
Former colonial ruler France, one of the top foreign investors in Senegal, has said it would like to see power pass to a younger generation. A senior U.S. official has said Wade's bid for a third term could jeopardise the country's strong record of democracy and stability.
At least four people, including a police officer, have died in protests since late January when Senegal's top legal body confirmed Wade had the legal right to seek a new term despite a 2001 constitutional amendment setting a two-term limit.
Wade, who came to power in 2000, argued his first term should not be counted because the rule was added to the constitution after his first term had already started.
Wade's opposition has failed to unite around a single candidate, boosting the incumbent's chances in the first round.