UNITED NATIONS — In an exceptional move, the United Nations secretary general, Ban Ki-moon, on Wednesday ousted his top official in the Central African Republic after repeated accusations that peacekeepers there committed what Mr. Ban called “terrible crimes of sexual violence” against civilians, including children.
The official, Babacar Gaye, a former general in the Senegalese Army who has served as the special representative of the secretary general in the Central African Republic, has resigned “at my request,” Mr. Ban said.
Dismissing a veteran and senior official is “unprecedented” in the United Nations system, Mr. Ban’s spokesman, Stéphane Dujarric, said. The gesture was clearly intended to signal that Mr. Ban takes the issue seriously.
“I cannot put into words how anguished and angered and ashamed I am by recurrent reports over the years of sexual exploitation and abuse by U.N. forces,” Mr. Ban said here, adding that he planned to talk to all his mission chiefs and force commanders in a videoconference on Thursday.
Mr. Ban said he would press them to “report allegations immediately, investigate thoroughly and act decisively” when they are made aware of any allegations of sexual abuse by United Nations personnel, both military and civilian.
“Failure to do so will have clear consequences,” he said. “I want our leaders to know they are accountable.”
Mr. Ban also said he would ask the Security Council to convene on Thursday in an emergency session.
His actions came a day after Amnesty International said that a police officer deployed by the United Nations in Bangui, the capital of the Central African Republic, had raped a 12-year-old girl during a search operation.
It was the latest in a series of accusations of rape and sexual abuse of children by foreign peacekeepers in that country. Since the mission was established last year, United Nations personnel have been accused in 11 separate cases of sexual exploitation and abuse, Mr. Dujarric said.
Even before the United Nations mission was established there, French peacekeepers sent to protect civilians were accused of sexually abusing boys in the capital over a six-month period that began last December. The United Nations uncovered the allegations but was accused of mishandling its own inquiry. France has said it is investigating but has yet to announce any charges.
Mr. Ban has appointed an independent panel to review how the United Nations handled that episode. Its report is due later this year.
Before taking over as the United Nations envoy in the Central African Republic, Mr. Gaye was the military adviser to the undersecretary general for peacekeeping, Hervé Ladsous, from 2010 to 2013, after which he became the United Nations envoy to the Central African Republic. He was also a force commander for the peacekeeping mission in the Democratic Republic of Congo.
For years, the issue of how to stanch sexual abuse in its ranks has bedeviled the United Nations.
According to its own figures, there were nearly 80 allegations of sexual exploitation and abuse committed by United Nations personnel in 2014. This represents a decline in complaints, but given the tendency to underreport such crimes, even United Nations officials say the numbers could well be higher.
A separate internal inquiry into how the organization handles sexual abuse claims found that investigations tended to be mired in procedural matters, that commanders were not always held accountable for misconduct in their contingents, and that the most common form of punishment turned out to be sending the accused back home, where there were no guarantees of prosecution.
Mr. Ban’s remarks Wednesday signaled his frustration with that pattern. “I want member states to know that I cannot do this alone,” he said. “They have the ultimate responsibility to hold individual uniformed personnel to account, and they must take decisive preventive and punitive action.”
The United Nations cannot prosecute or punish perpetrators. That is left up to the countries that send their citizens to take part in United Nations missions.