GENEVA — The United Nations reported on Friday “extremely disturbing” new accusations of sexual abuse by European peacekeepers in the Central African Republic, adding to a long-running scandal that has reverberated at the highest levels of the world body.

The United Nations human rights chief, Zeid Ra’ad al-Hussein, called for further investigation of reports that members of a European Union peacekeeping contingent had raped two girls and had paid two others for sex. The girls were 14 to 16 at the time.

The acts took place in 2014 and 2015 and involved troops from Georgia and another European country, the girls told investigators. The other country has not been publicly identified.

In addition, United Nations human rights officials reported that a 7-year-old boy and a 9-year-old girl said they had been paid by French peacekeepers for oral sex and that they knew of other children who had been repeatedly abused by French troops.

“These are extremely serious accusations,” Mr. al-Hussein said, “and it is crucial that these cases are thoroughly and urgently investigated.”

The latest cases, uncovered by investigators in early January, add to concerns about the failure of the United Nations to curb what Rupert Colville, a spokesman for the Office of the High Commissioner on Human Rights, called the “constant horror story of allegations” that have dogged international peacekeeping troops.

“Far too many of these crimes continue to go unpunished, with the perpetrators enjoying full impunity,” Mr. al-Hussein said in a statement. “This simply encourages further violations,” he added, emphasizing the obligation of nations to investigate and prosecute abuse and to ensure that victims receive redress.

Mr. al-Hussein said that he had discussed the latest accusations with the French, Georgian and European Union authorities, and that he was “heartened” by their initial responses.

He added, however, that there was no doubt that all foreign military forces, regardless of whether they serve under the United Nations umbrella, “must employ much stronger and more effective actions to prevent further abuse and exploitation.”

“What is abundantly clear in the Central African Republic is that it has been rampant,” Mr. Colville said, noting that around 10 international peacekeeping contingents had now been implicated in cases of sexual abuse. “For whatever reason, not enough is being done to stop this happening. The message doesn’t seem to have got through.”

The European Union said in a statement that it took the accusations “very seriously” and that it had sent an expert to the human rights office to discuss a response. It added that the bloc had a policy of zero tolerance for sexual abuse or criminal conduct, but that responsibility for any investigation, disciplinary or criminal action rested with the home countries of the accused.

United Nations investigators suspect that French peacekeepers abused boys in Bangui, the capital of the Central African Republic, in 2014. The French authorities are now investigating the cases, but there have been no convictions to date, Mr. Colville said.

The United Nations response to those reports was criticized by an independent panel appointed by Secretary General Ban Ki-moon, which said in a report last month that officials had “turned a blind eye to the criminal actions of individual troops” and had failed to protect or aid child victims of sexual abuse.

Instead, the report found, the United Nations human rights office had focused on the conduct of a senior staff member who leaked to the French authorities an internal report that did not redact the names of victims. The staff member was exonerated.