A UN team recently interviewed five girls and a boy who claimed their abusers were part of French and European Union military operations in the troubled African country, the office of High Commissioner for Human Rights Zeid Raad al-Hussein said, AP reported.

The sexual abuse reportedly took place in 2014 in or near a camp for displaced people near M’Poko airport in CAR’s capital, Bangui, but only came to light in recent weeks, the latest in a string of similar allegations.

France, Central African Republic’s former colonial ruler, deployed several thousand troops to the country in late 2013 as violence in the region sent thousands fleeing from their homes. An African Union mission that began in April 2014 was taken over by a UN peacekeeping force five months later, while the EU force ended an 11-month mission in March last year.

“These are extremely serious accusations and it is crucial that these cases are thoroughly and urgently investigated,” Zeid said in a statement. “We will continue to closely follow up on these cases, and any others which emerge, as the UN team on the ground continues its investigations.”

The UN can report the allegations but countries themselves are responsible for prosecuting their troops over such crimes.

The UN rights office said three of the girls said they believed their abusers were members of a Georgian contingent within a European Union force, and another girl was allegedly abused by a soldier from another European country that was not named because “additional corroboration is needed” in that case.

UN staffers interviewed a 7-year-old girl and 9-year-old boy who said they had been abused by troops in the French “Sangaris” operation. The girl said she had performed “oral sex on French soldiers in exchange for a bottle of water and a sachet of cookies,” the statement from Zeid’s office said.

A spokesman for Zeid’s office said the 7-year-old was the youngest alleged victim so far in any of the CAR cases. The two children said other children were abused in a similar fashion in repeated incidents involving several French soldiers, according to the statement.

The UN is under pressure to act more quickly after an independent panel last month described the world body’s “gross institutional failure” in handling similar allegations in CAR against French and other peacekeepers. The report said the months-long delay in addressing children’s accounts of abuse had led to even more reported assaults.