After repeated delays, the run-up to the presidential and parliamentary vote turned violent in the capital at the weekend. Final rallies were canceled due to clashes between rival supporters, security forces opened fire on crowds and the main presidential challenger was prevented from campaigning.

The polls - which pit President Joseph Kabila against 10 rivals while more than 18,500 candidates compete for 500 seats in parliament - will test the central African nation's progress toward stability after decades of misrule and two wars in the last 15 years.

United Nations troops and helicopters from Angola and South Africa have been called on to ferry election material to 60,000 polling stations across a nation the size of Western Europe with little infrastructure so some 32 million people can vote.

Provisional results are due on December 6.