Polls are due to open in the Central African Republic in delayed presidential and parliamentary elections aimed at restoring stable government after years of turmoil.
Thirty candidates are vying to replace interim leader Catherine Samba-Panza.
UN peacekeepers hope to stop a repeat of the violence three weeks ago during a referendum on a new constitution.
The CAR has been torn by sectarian violence since the Muslim Seleka alliance seized power in March 2013.
A band of mostly Christian militias, called the anti-Balaka, then took up arms against the Seleka.
In January 2014, a transitional government was formed but elections have been postponed four times since February 2015 due to insecurity and logistical challenges.
Three candidates are considered frontrunners for the presidency.
Two of them – Martin Ziguele and Anicet Dologuele – were prime ministers under late President Ange-Felix Patasse. The third, Karim Meckassoua, is a Muslim who served as a minister under President Francois Bozize until he was ousted in 2013 by Seleka rebels.
Observers say a second round is likely and expect it to be held by the end of January.
Elections are also taking place for the 105-seat National Assembly.
After seizing power, the Seleka rebels installed Michel Djotodia as the first Muslim leader of the majority Christian country.
But under pressure from regional leaders and former colonial power France, Mr Djotodia stood down and was succeeded by Ms Samba-Panza.
Mr Djotodia and Mr Bozize are both in exile and face UN and US sanctions over violence in the country.