At least 42 Muslim herders are being held captive by anti-Balaka rebel fighters in the Central African Republic (CAR) and are at risk of being sexually assaulted, according to a report.

One family of Peuhl herders recounted incidents of rape, murders and deliberate starvation during 14 months of captivity in the southwest village of Pondo in interviews to Human Rights Watch (HRW). The researchers called on the United Nations on Wednesday to end the violence and free the dozens of people who are still being held captive. The vast majority are women and girls, some held for more than a year, according to HRW.

"Holding civilians captive, killing children and sexually enslaving women and girls are shocking tactics by these anti-Balaka and amount to war crimes," said Lewis Mudge, Africa researcher at HRW.

"U.N. peacekeepers and government officials who have already taken bold steps to free one group of ethnic Peuhl should urgently intervene to free the others and arrest their captors," he added.

At least 5,000 people have died in violence between the mostly Muslim Seleka rebels and the Christian anti-Balaka group in the past year. The Seleka rebels seized power in March 2013, overthrowing the president who had been in power for a decade in the majority Christian country. Their leader stepped down in January, setting off a series of reprisal attacks by the anti-Balaka militia. Almost a million, about a quarter of the population, have been displaced by violence since then.

Thirteen surviving members of the Peuhl family were freed by peacekeepers of the United Nations Multidimensional Integrated Stabilization Mission in the CAR (MINUSCA) and local authorities this month. One young woman, about 18 years old, said she had been raped by multiple anti-Balaka fighters during her captivity, according to HRW.

"I was taken as a wife by the anti-Balaka," she said. "It was against my will, I did not want to accept it. It was not just one man; it was with many different men. They would just take me. They brutalized me, and I am now pregnant."

About 8,000 African peacekeepers and 2,000 French troops are working to secure the country, which is the size of Texas. France, however, has announced it will pull out a substantial part of its forces by the end of this year. The U.N. remains at 80 percent of its planned capacity but U.S. Ambassador to the U.N. Samantha Power said the Security Council was "very favoribly disposed" toward adding 1,000 troops. The European Union force of about 750 soldiers left the CAR in March.

Al Jazeera and wire services