Abidjan, Ivory Coast (CNN) -- Campaigning for runoff elections in the Ivory Coast began Saturday with violent face-offs between young supporters of the two rival candidates.
President Laurent Gbagbo faces challenger Allassane Ouattara in balloting November 28.
At least 20 people were wounded after youths clashed Friday afternoon in front of the opposition coalition's headquarters. Police spokesperson Diagouri Gnawa Honoré appeared later on national television to appeal for calm.
Among the injured was French journalist Laurent Despas, who was severely beaten, according to Koaci.com, the online blog he created.
"We're shocked by his lynching by the armed hooligans Friday afternoon," the website said. "The hooligans unleashed their hatred with extreme violence."
The post said that Despas was attacked and beaten by a mob "armed with machetes and swords with the intent to kill him."
Gbagbo finished slightly ahead of Ouattara in the initial election last month with 38 percent of the vote to the challenger's 32 percent.
Ouattara, a former economist for the International Monetary Fund, was banned from previous races in the west African nation that was plunged into instability by a 2002 civil war. Thousands died in the conflict that pitted government forces against discontented Muslims living in the north.
Gbagbo has stoked tensions by accusing Ouattara of masterminding the civil war. Ouattara has denied the allegations.
Observers hope the election, delayed for five years, will help bring lasting peace to the divided nation. But there are fears of escalating violence.
The United Nations has been taking measures to ensure an orderly second round of elections, according to Hamadoun Toure, spokesman for the U.N. Operation in the Ivory Coast.
Toure expects a high turnout for the runoff. More than 83 percent of eligible voters participated in the first round, he said.
The runoff elections were originally scheduled for November 21. The Independent Electoral Commission said it proposed November 28 as the date for the second round of the race.
CNN's Umaro Djau contributed to this report.