Thousands of opposition supporters clashed with riot police Tuesday and burned President Joseph Kabila's campaign posters ahead of weekend elections.
Congolese security forces swung truncheons and fired tear gas at the protesters, who threw Molotov cocktails and chunks of masonry in the streets of Kinshasa, the capital. There was no immediate word on casualties.
Young people made up most of the 4,000-person crowd in a poor neighborhood. One onlooker said they were outraged by their poverty after years of war and corrupt rule that have hobbled their vast, mineral-rich nation.
"Our poverty stems from our politics, which don't work. Our leaders are corrupt and sell our riches overseas while we have nothing," said Bob Massoud, 23, an artist. "We're mad because we're suffering. Everyone is angry."
The atmosphere is tense in the Democratic Republic of Congo, formerly known as Zaire, in the run-up to Sunday's vote -- the first free, multiparty elections for president and Parliament in decades.
The protesters, representing two opposition parties, allege that irregularities in the voters' roll and the printing of 5 million spare ballots suggest that the vote is being fixed. Election authorities reject the charges.
Kabila is believed to be the front-runner among 33 candidates seeking to lead the country out of a transition period after back-to-back wars that ended in 2002.
Many Congolese are grateful to Kabila for negotiating a settlement that ended five years of war sparked by his father, Laurent, a former rebel leader who took power after his troops chased longtime dictator Mobutu Sese Seko from the country in 1997.
Kabila inherited the presidency in 2001 after his father was assassinated and has led a national unity government overseeing peace deals that ended the wars.