Meanwhile a seven-year-old girl and a nine-year-old boy said they were abused by French troops.
The troops were sent to stem violence between Christian militias and largely Muslim rebels.
The rebels seized power in March 2013 - in response, the militias took up arms against them.
The abuse is alleged to have taken place near a camp for displaced people near Bangui Airport in 2014 but only came to light in recent weeks during interviews with a UN team.
UN High Commissioner for Human Rights Zeid Raad al-Hussein said he was "extremely alarmed" at the continuing allegations against peacekeeping troops.
Last December an independent panel criticised the UN`s handling of abuse allegations in the CAR, calling it "seriously flawed" and a "gross institutional failure".
It accused senior UN officials of abusing their authority by failing to take action over allegations of abuse by soldiers troops from France, Equatorial Guinea and Chad.
France sent 2,000 troops to to its former colony in 2013 and began handing over responsibility to UN peacekeepers last year.
More about:
-1780923278.jpg&h=190&w=280&zc=1&q=100)
