Even as UN Secretary General Ban Ki Moon declared "zero tolerance" over sex-crime abuses by its peacekeepers recently, latest investigations have found that some personnel in the Central African Republic (CAR) allegedly paid minor girls for sex, a report said.

At least four UN peacekeepers allegedly paid $0.50-3 for girls as young as 13 in exchange for sex at M'Poko camp in national capital Bangui, reported The Washington Post.

The camp, which houses 20,000 internally displaced people, is located near the international airport of the city and is run by  humanitarian organisation under the United Nations High Commissioner for Refugees.

"The M'Poko camp is unfortunately a place where horrible, unacceptable things happen to women and children," Anthony Banbury, UN assistant secretary-general for field support, told the daily. "In some cases, we have credible allegations that UN personnel have committed these crimes."

Unofficial reports suggest the peacekeepers are from France, Morocco, Burundi and Gabon.

Earlier, Human Rights Watch had reported 25 cases of sexual violence in Bangui during September-December 2015.

"M'Poko is a lawless zone run by anti-balaka thugs a few hundred metres away from the international airport. The camp is not being protected, and women are being raped," the daily quoted Human Rights Watch researcher Lewis Mudge as saying.

In 2013-14, at least 14 peacekeepers from France, Chad and Equatorial Guinea had allegedly raped six boys aged between 9 and 15, stated the report.

However, UN official say the number of alleged cases of sexual violence has come down from 83 in 2008 to 51 in 2014 as a result of effective intervention. Meanwhile, critics have reportedly dismissed the claim, saying the figures are incomplete as several cases are not reported.