UN peacekeeping operations in the Central African Republic suffer from "gaps in the force's capacity to respond" that "have been evident" since their September 2014 deployment, Amnesty International said Monday.
About 12,000 peacekeepers are currently in CAR, which was plunged into violence in March 2013, when mainly Muslim Seleka rebels overthrew Christian president Francois Bozize.
Thousands have been killed and about 1 million displaced in inter-religious violence.
The weaknesses of the UN mission – known as MINUSCA - became evident in September, when it took about two days to intervene against a three-day surge of violence in the capital, Bangui, that killed at least 75 people, Amnesty said.
The UN mission has too few troops, who lack equipment and the capacity to gather intelligence, according to the report. Many of whom "are performing below expected standards," it stated.
MINUSCA troops have been involved in a string of scandals involving peacekeepers allegedly sexually abusing local women, the human rights group pointed out.
The UN – which is due to repatriate 120 peacekeepers from Congo due to such allegations – is expected to name all the countries implicated in the scandals this month.
The UN welcomed the release of the Amnesty International report and supports its findings, said Stephane Dujarric, the spokesman for UN Secretary General Ban Ki-moon, in New York.
"These kinds of reports are important for peacekeeping missions in order to get sort of an outside look and see how they can improve their way of working," he said.
Amnesty also accused the UN mission of not providing sufficient security to Muslims fleeing Christian militiamen in CAR.
MINUSCA protects civilians without discrimination, but sometimes it is confronted with sudden upsurges of violence "and we are not there for urban guerrilla warfare," responded lieutenant colonel Adolphe Manirakiza, a spokesman for the UN mission in Bangui.
The UN mission to CAR operated better late last year, but "there is little guarantee that, without further measures to strengthen MINUSCA, new outbreaks of violence will not continue to threaten the stability of the country," Amnesty said.
The group interviewed 85 people for the report, including MINUSCA staff, officials, members of armed groups, witnesses and victims.
CAR will on Sunday hold the second round of a presidential election seen as a requirement toward stabilizing the country.