The United Nations is urging calm in the Democratic Republic of Congo after European observers described widespread voting irregularities in this week's presidential election.

U.N. mission chief Roger Meece says any grievances must be addressed through peaceful means.

A preliminary European Union report says election observers saw ballot box stuffing, ballot shortages, and said some people were turned away from the polls.

U.S.-based monitors from the Carter Center also report problems. But the African Union and other African observers call the election a success.

Witnesses Thursday say they saw thousands of plastic bags with ballots piled up in a parking lot in Kinshasa. They say ballots blew away and others were soaked by rain when some of the bags broke open.

An official with Congo's Independent National Election Commission told VOA that these reports are “exaggerated” and that everything is in order.

President Joseph Kabila is running for re-election against 10 challengers. Three presidential candidates have called for the vote to be annulled.

The election was originally set to last one day but stretched into three because of irregularities. Final results are expected before President Kabila's term expires on December 6.