Thousands of these women have died because of lack of food in camps for internally displaced people in Nigeria's northeast after they were rescued from Boko Haram, Amnesty says.
In the report titled "They betrayed us,
" it is alleged that five women said they were raped by soldiers in late 2015 and early 2016 in a displacement camp in Bama, Borno state.
Women interviewed by Amnesty said they were beaten and called "Boko Haram wives" by security officials whenever they complained about their treatment.
The report says that members of the Nigerian military and a local vigilante group Civilian Joint Task Force (Civilian JTF) "separated women from their husbands and confined them in remote 'satellite camps' where they were raped, sometimes in exchange for food."
Ten women in the Bama camp told Amnesty they were forced to date security officials to get food. One woman said a member of the JTF vigilante group raped her after he brought her food, telling her: "I gave you these things, if you want them, we have to be husband and wife."
"Sex in these highly coercive circumstances is always rape, even when physical force is not used, and Nigerian soldiers and civilian JTF members have been getting away it," Osai Ojigho, Director of Amnesty International Nigeria said.
"They act like they don't risk sanction, but the perpetrators and their superiors who have allowed this to go unchallenged have committed crimes under international law and must be held to account."
Deadly terror group
Boko Haram, described as the third deadliest terror group
by the Global Terrorism Index, has unleashed waves of brutal attacks across parts of northern Nigeria, bombing schools, churches and mosques and kidnapping women and children in a conflict that spans nearly a decade.
The conflict has killed thousands of people and also internally displaced two million people, according to the Internal Displacement Monitoring Centre.