BAMAKO, Mali (AP) — Voters in Mali are heading to the polls to select a president amid increasing attacks by extremist groups linked to al-Qaida and the Islamic State group.

Voters expressed concern about being targeted after al-Qaida's Mali branch warned against going to the polls. Deadly communal clashes between ethnic groups and accusations of heavy-handed counterterror operations also have complicated what President Ibrahim Boubacar Keita hopes will be a victory giving him a second term.

Keita, who was elected in 2013, faces 23 candidates in the first round.

His main challenger, Soumaila Cisse, has criticized the president for not addressing Mali's rising insecurity.

Several political parties have expressed doubts about a valid election after duplicate and fictitious polling stations were listed on the electoral commission's website. More than 8 million voters are registered.