Amnesty published a 32-page report Wednesday indicating there was mass displacement, arbitrary detention, sexual violence and the use of child soldiers among rebel forces in the north of the country.
"The entire north of the country has been taken over by armed groups who are running riot," Gaetan Mootoo, Amnesty International's West Africa researcher, said in a statement from New York. "Tens of thousands of people have fled the region, creating a humanitarian crisis in southern Mali and in neighboring countries."
Mootoo led a delegation to Mali last month. The rights group said it found evidence rebel forces gang raped women and girls, though all parties to the conflict are believed to have committed human rights abuses. National forces are suspected of summarily executing prisoners and of torture and other abuses.
Members of the Economic Community of West African States had said they were growing frustrated with parties loyal to military leaders who overthrew the government early this year.
Coup leaders overthrew the civilian government in March out of frustration with its inability to handle a northern rebellion. Rebel leaders in the north have since declared autonomy for their part of the country.