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 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.

Despite a ban on further election rallies, Tshisekedi has called on his supporters to gather Sunday in the capital, Kinshasa — this after they were blocked the day before at the city’s airport. Security forces on Saturday fired live ammunition and tear gas to disperse the crowd, killing at least three and wounding several more.

Preparations for the election that pits more than 18,000 candidates vying for 500 seats in the general assembly were said to be running behind schedule. Bad weather delayed the delivery of ballot materials to 60,000 polling stations spread across a country the size of Western Europe but with few paved roads. It was not clear if the ballots would reach polling stations in Congo’s remote interior by Monday.