Updated

Secretary-General Ban Ki-moon says the United Nations will establish a commission to investigate reports of atrocities in Central African Republic.

The U.N. chief told reporters Monday he is "gravely concerned about the imminent danger of mass atrocities" in the country which "descended into chaos" this year.

Mainly Muslim rebels overthrew the Christian-led government in March.

Ban said the entire population of 4.6 million people — half of them children — is affected, and the U.N. is scaling up its humanitarian response and sending in human rights monitors.

He said African and French troops are already making a difference but "we must do more to meet this test of global solidarity."