At least two people have been killed during riots in the central Democratic Republic of Congo town of Mbuji Mayi.
Mbuji-Mayi is known for its diamond trading
Thousands of opposition activists took to the muddy streets of DR Congo's diamond capital in protest at the planned postponement of elections.
They burnt tyres on main streets and then set fire to the offices of three parties in the government coalition.
Hundreds of policemen intervened and gunshots were fired. The election are part of a deal to end years of war.
The BBC's Arnaud Zajtman in DR Congo says Mbuji Mayi is usually a busy trading centre where small stones worth millions of dollars change hands each month.
Although the land is rich, the two million inhabitants of this mining centre don't see much of this wealth, our correspondent says.
They have never had access to tarmac roads, electricity and running water.
This has created a fertile ground on which the Union for Democracy and Social Progress (UDPS) has flourished.
The protesters took to the streets behind portraits of veteran UDPS leader Etienne Tshisekedi.
Local UDPS representative Sana Tshilunday said that three civilians were killed by the police and provincial governor Dominique Kanku confirmed that two people were killed.
Mbuji Mayi is located in the centre of DR Congo, a country the size of western Europe that is emerging from a five-year war that has claimed an estimated three million lives, mainly from hunger and disease.
The former belligerents now sit in a power-sharing government and are supposed to organise elections next month.
But sporadic fighting, corruption and lack of political mean the elections look set to be delayed by at least six months, a prospect that is totally rejected by the Congolese opposition.