Violence has marred preparations for Monday's presidential and legislative elections in the Democratic Republic of Congo with at least three people reported killed.

International observers and U.N. Secretary-General Ban Ki-moon called for restraint and said the Congolese government is mainly responsible to see the balloting is peaceful.

It is only the second multi-party poll since independence and since the large central African nation was torn apart by two wars, the last one ending in 2003.

Incumbent President Joseph Kabila, who is running against 10 opposition candidates, is widely expected to win re-election. He has been in power since 2001, when he assumed the presidency after the assassination of his father, Laurent Kabila. The last presidential election was in 2006.

His strongest challenger, long-time opposition leader Etienne Tshisekedi, has apparently canceled his plans to ignore a ban on public gatherings and hold a rally Sunday in the capital, Kinshasa. His advisers say they feared for his safety. On Saturday, Congolese police for several hours blocked Tshisekedi and his supporters from trying to enter the city from the airport, firing ammunition and tear gas that left at three dead, several more wounded.

The capital was reported calm on Sunday, described as a “Day of Reflection” in Congo, with no gatherings of large crowds. Government officials say the vote will proceed as scheduled.

Tshisekedi has accused the head of the U.N.'s large peacekeeping force in Congo of a bias against him. He has called for removal of mission chief Roger Meece, who once served as the U.S. ambassador in the county.

Preparations for the election that pits more than 18,000 candidates vying for 500 seats in the general assembly are said to be running behind schedule. Bad weather delayed the delivery of ballot materials to tens of thousands of polling stations across a country the size of Western Europe. With few paved roads, it was not clear if ballots would reach polling stations in Congo's remote interior by Monday.