The United Nations expressed alarm Friday over reported mob lynchings and other reprisal killings of Tuaregs and Arabs as the Malian army retakes control of the north of the country.
Adama Dieng, a special adviser to UN leader Ban Ki-moon on the prevention of genocide, said there have been "serious allegations" of summary executions by the Malian army, which could amount to "atrocity crimes."
French forces intervened in Mali three weeks ago to halt an Islamist advance on the capital and, with the Malian army, have taken back large chunks of territory from the militant groups.
The Islamists have already been accused of brutal killings and dismemberments as they imposed a harsh sharia law during their nine months in control.
The International Committee of the Red Cross has sought access to prisoners taken by the Malian army and the Human Rights Watch and Amnesty International groups have demanded an inquiry into reports of reprisal killings.
"While the liberation of towns once under the control of the rebel and extremist groups has brought hope to the populations of northern Mali, I am deeply concerned at the risk of reprisal attacks against ethnic Tuareg and Arab civilians," Dieng said in a statement.
"There have been serious allegations of human rights violations committed by the Malian army, including summary executions and disappearances, in Sevare, Mopti, Niono and other towns close to the areas where fighting has occurred," he added.
"There have also been reports of incidents of mob lynching and looting of properties belonging to Arab and Tuareg communities. These communities are reportedly being accused of supporting armed groups, based simply on their ethnic affiliation."
The special envoy said the Malian army has a "responsibility to protect all populations, irrespective of their race or ethnicity."
"I am deeply disturbed by reports of violations committed by the army, and by reports that the armed forces have been recruiting and arming proxy militia groups to instigate attacks against particular ethnic and national groups in northern Mali."
The envoy added that targeting "ethnic or religious groups in an armed conflict and if such abuses are carried out in a widespread and systematic way, could constitute atrocity crimes."
The International Criminal Court has said it will open an investigation into events in Mali.