Six more children in the Central African Republic (CAR) have accused European soldiers of sex abuse, the United Nations said on Friday, with one official saying such abuse was "rampant" there.

The European Union, Georgia, France and another unnamed European country are investigating the alleged crimes, including rapes, mostly committed in 2014 in or near a camp for displaced people next to the airport at Bangui, CAR's capital.

One of the girls interviewed by UN staff said that in 2014 when she was 7 years old she had performed sexual acts on French soldiers, part of the EU's EUFOR force, "in exchange for a bottle of water and a sachet of cookies", a UN statement said.

"What is abundantly clear in the Central African Republic is that it has been rampant. We're talking, I don't know the exact number of contingents involved, something like 10 now, both UN and non-UN, which is truly shocking," UN human rights spokesman, Rupert Colville, told a news briefing in Geneva.

"What this does show is this a problem with the armies, with the military forces, and for whatever reason not enough is being done to stop this happening," he said.

Convictions have been "far, far too few", Colville said, recalling just one conviction of a French soldier.

Accusations of mishandling

Last month, an independent review panel accused the UN and its agencies of grossly mishandling allegations of child sexual abuse in 2013 and 2014 by international peacekeepers in CAR.

UN sources in New York said on Friday that five new allegations of abuse committed in 2014 and 2015 were also made against UN troops from Morocco, Niger, Bangladesh, Democratic Republic of Congo and police from Senegal.

Referring to the CAR cases, that the UN said had only come to light in recent weeks, UN High Commissioner for Human Rights Zeid Ra'ad Al Hussein said, "These are extremely serious accusations and it is crucial that these cases are thoroughly and urgently investigated."

"States have an obligation to investigate, prosecute and ensure that the victims receive the redress to which they are entitled."

Georgia's Defence Ministry said in a statement it would investigate the allegations "in great detail and in case such grave crimes are proven, perpetrators of such crimes will be brought to justice".

It said that "every individual, who was under a direct obligation to investigate the facts and establish the truth of this matter in 2014, will be suspended from carrying out their professional duties" pending the investigation.

The EU said it followed a zero-tolerance policy on sexual misconduct and criminal activity.

Thousands of foreign peacekeepers have been deployed in CAR after mainly Muslim rebels seized power in the majority Christian nation in 2013, provoking reprisals from Christian militias and fuelling religious and inter-communal violence that has killed thousands.

"All these peacekeeping forces have played a very important role, and we shouldn't ignore that. But at the time time we can't ignore the fact that hopefully a small number in these armies are committing appalling abuses," the UN's Colville said.

"It's been a constant horror story really of allegations against peacekeepers, UN peacekeepers in many countries."