CAR conflict erupted in March when Seleka, a Sunni rebel coalition, overthrew the government by force. Fatou Bensouda, chief prosecutor at the International Criminal Court, said Friday the conflict has "gone from bad to worse" since anti-balaka, a Christian militia, took up arms against their Sunni rivals.
Bensouda said from The Hague accounts of "extreme brutality" prompted her to open a preliminary examination into CAR violence.
In December, the prosecutor warned all parties to the conflict in CAR were at risk of prosecution for war crimes.
Western and regional leaders expressed optimism when Catherine Samba-Panza was selected recently as the interim CAR president to help lead the country out of the crisis.
Human Rights Watch, however, said this week it suspected Chadian peacekeepers were helping Seleka rebels relocate from their bases Bangui to the north of the country. HRW said there were signs Seleka rebels "tortured and killed" civilians in parts of the region in January.
"My office will also be engaging with the CAR authorities with a view to discussing ways and means to bring perpetrators to account, including at the national level," Bensouda said.
CAR is a party to the Rome Statute that created the ICC.