Kurdish Peshmerga forces and militias in northern Iraq have demolished thousands of homes in a concerted effort to remove Arab communities, Amnesty International says.
They did so in revenge for the Arabs' perceived support for so-called Islamic State (IS), a new report alleges.
Amnesty says Kurdistan Regional Government forces might have committed war crimes in areas recaptured from IS.
But a KRG spokesman said the damage was the result of fighting and air strikes.
Dindar Zabari told the Reuters news agency that the US-led coalition against IS had also requested that civilians be kept away from areas close to the frontline, and that Kurds too had been prevented from returning to some recaptured villages.
Amnesty said its report was based on a field investigation in 13 villages and towns and put together from testimony gathered from more than 100 eyewitnesses and victims of forced displacement.
The group said its findings had been corroborated by satellite imagery that showed evidence of widespread destruction carried out by Kurdish forces - in some cases by Yazidi militias and in other cases by Kurdish armed groups from Syria and Turkey operating in co-ordination with the Peshmerga.
"The forced displacement of civilians and the deliberate destruction of homes and property without military justification, may amount to war crimes," said Amnesty's Senior Crisis Response Adviser, Donatella Rovera.
Arab residents forced to vacate their homes were now prevented by KRG forces from returning to recaptured areas, Amnesty said,
"Tens of thousands of Arab civilians who were forced to flee their homes because of fighting are now struggling to survive in makeshift camps in desperate conditions," Ms Rovera said.
"Many have lost their livelihoods and all their possessions and with their homes destroyed, they have nothing to return to," she added.
"By barring the displaced from returning to their villages and destroying their homes KRG forces are further exacerbating their suffering."
The Amnesty report follows a UN report on Tuesday which says that violence suffered by civilians in Iraq "remains staggering", with at least 18,800 killed between 1 January 2014 and 31 October 2015.
The UN said the worst excesses were committed by IS, who are responsible for systematic and widespread violence, including holding some 3,500 mainly women and children as slaves.
But it too said that some alleged abuses were carried out by troops, militiamen and Kurdish forces.