A Parisian prosecutor says an investigation is under way into claims French soldiers in the Central African Republic sexually abused children.
France sent an initial 1,600 troops to the country in December 2013 after violence flared following a coup.
On Wednesday, the Guardian newspaper reported that a United Nations worker was suspended after leaking a report on abuses by French troops.
It says a UN report claimed children as young as nine were abused.
Agnes Thibault-Lecuivre, a spokeswoman for the Paris prosecutor's office, said an investigation had been under way since July 2014.
The Guardian said that the alleged abuse took place between December 2013 and June 2014 at a centre for internally displaced people in the Central African Republic capital, Bangui.
Quoting an internal UN report, it says that in one case, a nine-year-old boy and his friend were forced to carry out a sex act by two French soldiers.
In some cases, it says, children were able to give good descriptions of the French soldiers alleged to be involved.
A spokesman for France's Ministry of Defence said in a statement: "The defence ministry has taken and will take the necessary measures to allow the truth to be found.
"If the facts are proven, the strongest penalties will be imposed on those responsible for what would be an intolerable attack on soldiers' values."
The Guardian said a Swedish employee of the United Nations had been suspended after handing the internal UN report to French authorities.
A spokesman for the UN Secretary General said the leaking of an unredacted report constituted "a serious breach of protocol" and could endanger victims and witnesses.
France intervened in its former colony in December 2013, nine months after a rebel alliance, Seleka, captured the capital and ousted President Francois Bozize.
The country descended into ethnic and sectarian violence, with thousands of people fleeing their homes and the UN warning that there was a high risk of genocide.
The UN took over and expanded the African peacekeeping mission in September 2014.