Faced with mounting pressure to shed light on accusations that French soldiers sexually abused children in the Central African Republic, the United Nations said Friday suggestions of a cover-up were "offensive."

Revelations this week that an internal U.N. report was leaked last July to French authorities with allegations that French peacekeepers in the chaos-ridden country had sexually assaulted hungry children in exchange for food have sparked uproar.

Soldiers from Chad and Equatorial Guinea have been accused in a confidential U.N. report that also implicates French troops of sexually abusing children in Central African Republic, a non-governmental organization said Thursday.

The report by U.N. rights investigators cites testimony from two children who witnessed the sexual assault, said Paula Donovan of the AIDS-Free World organization, which has seen the report.

President Francois Hollande on Thursday vowed to "show no mercy" if French peacekeepers in Central African Republic were found guilty of raping hungry children in exchange for food.

According to a French judicial source, several children -- the youngest just nine -- allege that 14 French soldiers dispatched to the impoverished nation to restore order after a 2013 coup were involved in sexually abusing some of them in exchange for food.

French prosecutors have opened an investigation into claims that French peacekeepers sexually abused children as young as nine in the Central African Republic, a judicial source said Wednesday. 

The move followed claims reported in Britain's The Guardian newspaper that a senior U.N. aid worker had been suspended for leaking an internal report into abuse by French soldiers against children at a center for internally displaced people in the capital Bangui.

The United Nations warned Monday it had received only a fraction of the funds needed to address strife-torn Central African Republic's towering humanitarian crisis, forcing it to cut desperately needed aid.

"We must prevent the Central African Republic from becoming a forgotten crisis," said Claire Bourgeois, the U.N. humanitarian coordinator for the country.

A protester was killed and several others injured on Friday when a demonstration turned violent outside a U.N. base in the Central African Republic, a U.N. spokesman said.

Peacekeepers fired warning shots to push back some 400 protesters, some of whom were armed with knives and who tried to set fire to the base in Kaga-Bandoro, north of Bangui, said spokesman Stephane Dujarric.

Warring forces in the Central African Republic have agreed to a ceasefire deal after months of negotiations mediated by Kenya, Nairobi announced on Wednesday. 

The deal was signed between Joachim Kokate, a representative of the mainly Christian anti-balaka rebels, and ex-president Michel Djotodia of the predominantly Muslim ex-Seleka movement, the Kenyan presidency said in a statement. 

Mass abductions of children by groups like Boko Haram and the Islamic State are on the rise, with the practice now becoming a tactic of war, a U.N. envoy warned Wednesday.

Leila Zerrougui, the special representative for children and conflict, urged the Security Council to punish armed groups who target children with sanctions and strengthen measures to protect children in conflict.

Sixteen Cameroonians have been kidnapped in northeastern Cameroon in an alleged attack by armed militia from the Central African Republic (CAR), security sources said on Friday.

The attack took place on Thursday night in Gbabio village, near the border with the CAR, and is thought to have been led by rebel chief Abdoulaye Miskine.

France announced on Thursday it was reducing its troop numbers in the Central African Republic as it gradually hands over to a 8,500-strong U.N. peacekeeping force brought in to contain a deadly sectarian conflict.

"We are going to begin a first cutback phase in the following days, going from 2,000 to 1,700 men," army spokesman Gilles Jaron said.