BAMAKO // Rebels who had conquered northern Mali offered to pay the equivalent of $14 for a 13-year-old girl. When her family said no, they took her anyway.

A week later, she died in captivity, after she was repeatedly raped by a group of armed men.

That incident in April is one of hundreds of documented cases compiled by the United Nations in the past year that shed light on the sexual violence unleashed by insurgents - mostly Tuareg separatists rather than Al Qaeda-linked Islamists - during their occupation of a sparsely populated and inhospitable region in Mali.

Nine months later, the rebels have melted away into the desert as French intervention troops advance. For the women of the farming and cattle-herding communities, the prospect is that yet another peace deal will ignore the record of rape used as a weapon of war.

"The question of sexual violence is not treated as an urgent question, unfortunately," said Hannah Armstrong, an analyst on security in West Africa. The same Tuareg fighters now clamouring for negotiations "carried out raid-style attacks during which animals were stolen, slave-caste women raped repeatedly", she said in Bamako, Mali's capital.

A total of 211 cases of sexual violence - including gang rape, sexual slavery, forced marriages and torture - were committed during house-to-house operations or at checkpoints during 2012, according to the Office of the UN Special Representative on Sexual Violence in Conflict.

The cases, which have not been made public, were verified over the course of a two-week fact-finding mission in November, when a UN official met in person with witnesses and survivors of sexual assault. Their names were withheld out of concern for their safety as the perpetrators still held the affected areas.

Only a handful of peace agreements address such crimes. The likelihood is that in Mali conflict-related sexual violence will be brushed aside, as has happened in Libya since the fighting that toppled and killed Muammar Qaddafi.

A further complication is that those held responsible for the worst abuses against women are young Tuareg men of Malian origin who rescinded their claims of independence and are now making peace overtures. The separatist rebel group that unleashed the chaos, the National Movement for the Liberation of Azawad, known by its French acronym MNLA, lost control over its militants soon after it occupied the north and its fighters were seen attacking their own people.

During the rebellion, traditional patterns of subjugation re-emerged, with most of the reported abuses occurring after the armed groups seized Gao on March 31 and a day later when they took Timbuktu.

A 36-year-old woman in Gao was raped in her home by two light-skinned, turban-wearing men speaking Tamasheq, the language spoken by Tuareg, according to an account told to UN officials. They broke into her house to demand money and gold ornaments and came in a vehicle flying a yellow, black, red and green flag used by MNLA.

In the Tuareg quest to gain independence for northern Mali, they joined forces with groups such as Ansar Dine, led by a dissident Tuareg commander turned militant Islamist, only to be pushed aside later.

The MNLA's exclusion from the negotiating table may hobble efforts to find a long-term solution.

"There should be some kind of acknowledgement of the abuses the MNLA committed as that would go some way to introducing the notion that they have a credible political leadership," said Ms Armstrong, a specialist in the Sahel region.

The acquisition of livestock and women through raids are part of the traditional Tuareg style of warfare, while subjugation of people seen as low-caste is still considered acceptable among some families, according to Temedt, a Malian human-rights group that conducts anti-slavery advocacy.

Women and girls of the darker-skinned Bella community, whose people have historically been considered as slaves of the Tuaregs, were in particular targeted by Ansar Dine and the Movement for Unity and Jihad in West Africa, a militant Islamist group that has many Tuareg fighters in its ranks, according to UN experts who visited Mali during the turmoil.

"Witnesses and victims from the Bella slave caste told me attackers and looters were Tuaregs, not Islamists," Ms Armstrong said.

In one incident, a 15-year-old girl was forced into marriage to Abdul Haqim, a military commander for the Movement for Unity and Jihad in West Africa. Repeatedly raped for months by fighters in the militia base, she was released when she became pregnant, according to the UN investigators.

In Mali, based on cases reported by displaced survivors of sexual violence, rebels conducted "requisitions", or the abduction of women and girls, from a district to spend the night in their camps. Each night a different district would be required to provide a number of women and girls to the rebels. This, UN officials say, would suggest it was a tactic to subjugate local populations that was condoned by top commanders.

In the case of the conflict in Democratic Republic of Congo, sexual attacks provoke displacement to increase aggressors' access to resources.

"Women in war-torn societies can face specific and devastating forms of sexual violence, which are sometimes deployed systematically to achieve military or political objectives," according to the UN office for gender equality and the empowerment of women.

Among the internal refugees in the capital, Bamako, some women also tell stories of rape and abuse, Violet Diallo, a British social worker, said in an interview.

"In the north, especially, it's taboo to discuss anything that relates to sex." said Ms Diallo, who helps displaced women in Bamako. "What we hear is probably only the tip of the iceberg."