Nigerian soldiers have raped women and girls who fled the insurgency by militant Islamist group Boko Haram, Amnesty International has said.
Troops separated women from their husbands and raped them, sometimes in exchange for food, in refugee camps, the rights group added.
Thousands of people have also starved to death in the camps in north-eastern Nigeria since 2015, Amnesty said.
The military has repeatedly been accused of carrying out atrocities, and the US, during the presidency of Barack Obama, refused to sell weapons to Nigeria, citing concerns about the military's human rights record.
However, the Trump administration has decided to press ahead with the sale of military aircraft and weapons, which Nigeria sees as vital to defeat the insurgents.
Amnesty said it was "absolutely shocking that people who had already suffered so much under Boko Haram have been condemned to further horrendous abuse by the Nigerian military. Instead of receiving protection from the authorities, women and girls have been forced to succumb to rape in order to avoid starvation or hunger," it added.
Amnesty added that as the military recaptured territory from Boko Haram in 2015, it ordered people living in villages to move to satellite camps, in some cases "indiscriminately killing those who remained in their homes. At least hundreds, and possibly thousands, died in Bama Hospital camp alone during this time. Those interviewed consistently reported that 15 to 30 people died each day from hunger and sickness during these months," the rights group said. It added that at least 32 babies and children, and five women, have died in detention since 2016 at the notorious Giwa barracks.
Many of those detained were victims of abductions or forced marriages by Boko Haram, Amnesty said. "The detention of women and girls on the basis that they were allegedly married to Boko Haram members is unlawful under international human rights law and Nigerian law, and is discriminatory," it added.
In 2016, Human Rights Watch reported that 43 women accused officials of rape and exploitation in refugee camps in Maiduguri, the capital of Borno state. Shortly after the release of the report, President Muhammadu Buhari mandated the local government to investigate the allegations. Ten officials were arrested in December 2016 but nothing happened after that.