The top two presidential candidates in the Democratic Republic of Congo are holding final rallies in the capital Saturday, ahead of elections on Monday.

President Joseph Kabila and one of the main opposition challengers, Etienne Tshisekedi, are planning to rally supporters at adjacent sites in the center of Kinshasa.

An electoral observer from the U.S.-based Carter Center told VOA that the competing rallies are raising concern there could be violence between supporters of the rival candidates.

In previous campaigning, supporters of the two politicians have clashed repeatedly both in Kinshasa and in the country's second-largest city, Lubumbashi.

President Kabila's rally is planned for the Stade des Martyrs. Mr. Tshisekedi's rally is expected to be held less than 500 meters away in the Palais du Peuple.

Both men are also scheduled to arrive at Kinshasa's airport within an hour of each other, and both plan large processions of supporters into town.

Ten candidates are challenging President Kabila in Monday's presidential election, and more than 18,000 people are running for 500 seats in the national assembly.

Political analysts in Congo believe Mr. Kabila will win re-election, partly because much of the opposition vote will be split among three candidates.

On Friday, Congolese election officials said they are ready for Monday's vote. A senior electoral official, Jacques Djoli Eseng'Ekeli, told VOA that training for poll workers is complete and said all voting materials have been delivered to regional headquarters.

In Washington Friday, the State Department issued a travel alert warning U.S. citizens about potential unrest or disruptions related to the elections.

Mr. Kabila has been president since 2001, when he took office after the death of his father, Laurent. He won the country's last presidential election in 2006.

The United States, European Union and United Nations have expressed concern about election-related unrest and violence, and the International Criminal Court has said it will prosecute any perpetrators of election-related crimes.