The United Nations disclosed new details on Thursday about a series of sexual abuse allegations against its peacekeepers in the Central African Republic, saying that nine of the 13 cases reported in the past year involved children as young as 11 and that no one had yet been convicted.

The disclosures were made in a video news conference held with Diane Corner, the United Nations deputy head of the peacekeeping mission in the Central African Republic’s capital, Bangui.

Ms. Corner has been the ranking official at the mission since her superior, Babacar Gaye, resigned at the request of Secretary General Ban Ki-moon last week over the sex-abuse scandal, which Mr. Ban described as “terrible crimes against civilians, including children.”

She spoke a day after United Nations officials revealed that their peacekeepers in the Central African Republic had been accused in at least 13 instances of abuse in the past year, including the rapes of three women that were brought to the mission’s attention on Aug. 12, the same day Mr. Gaye stepped down.