According to France's Defence Ministry, the alleged abuse and killings took place between Dec 2013 & June 2014 at a centre for displaced people at M'Poko airport in the capital Bangul. The UN mission in the Central African Republic on Tuesday, August 11th launched a probe into the allegations.
The probe was opened following allegations made by London-based rights watchdog Amnesty International, which said the alleged incidents took place on August 2 and 3 as Rwandan and Cameroonian peacekeepers were conducting an operation in the capital, Bangui.
In an initial response, UN Secretary-General Ban Ki-moon said he was "dismayed and disappointed" by the latest claims of sexual abuse by peacekeepers, his spokesman Stephane Dujarric told reporters in New York.
"Our evidence strongly suggests that a UN peacekeeper raped a young girl and that other UN peacekeepers indiscriminately killed two civilians," said Joanne Mariner, Senior Crisis Response Adviser at Amnesty International.
The UN mission, known by its French acronym of MINUSCA, said through its spokesman Hamadoun Toure that it was "not aware" of the allegations but was taking the matter "very seriously."
"We have opened a probe," Toure told AFP, saying the mission would seek "established and verifiable proof."
Dujarric said the UN chief was taking the situation "very seriously" and was expected to issue a formal statement.
"No misconduct of this nature can be tolerated," he told reporters. "This is clearly not only not normal, it is not acceptable. The secretary general is considering the situation very seriously."
The two alleged incidents took place during an operation to arrest a former rebel chief in the Muslim PK5 district of the capital on August 2 and 3 in which five people were killed, including a Cameroonian peacekeeper.Dozens of people were also injured.
Amnesty said it had interviewed 15 witnesses immediately after both incidents, as well as the girl and members of her family.
A nurse who examined the girl found medical evidence consistent with sexual assault.
"The girl had been hiding in a bathroom during a house search at approximately 2:00 am on August 2. A man allegedly wearing the blue helmet and vest of the UN peacekeeping forces took her outside and raped her behind a truck," a statement said.
"When I cried, he slapped me hard and put his hand over my mouth," she told Amnesty.
The search followed earlier deadly clashes in the area.
UN peacekeeping forces returned there the following day. Witnesses told Amnesty they were not under any threat but began shooting indiscriminately.
Amnesty said the soldiers killed Balla Hadji, 61, and his 16-year-old son Souleimane. Balla was apparently shot in the back, while his son was shot in the chest.
A neighbour who witnessed the killings said the soldiers appeared to "shoot at anything that moved."
Hadji's family said the UN troops did not help them to transport the wounded man and boy to hospital. Rather than provide assistance, witnesses said, the peacekeepers fired another round when the daughter tried to cross the street to reach her injured relatives.
The UN mission in the poor restive country has been under a cloud after claims that it dragged its feet following allegations that more than a dozen French soldiers dispatched to restore order after a 2013 coup sexually abused children in exchange for food.