Congolese police violently broke up a banned protest in the capital Kinshasa on Wednesday, leaving several people wounded, and one opposition leader said more marches were planned against last week’s vote. Disputes over the Dec. 20 presidential and legislative elections threaten to further destabilise Democratic Republic of Congo, which is already grappling with a security crisis in eastern areas that has hampered development in the world’s top producer of cobalt and other industrial minerals and metals.