Amnesty International has accused armed Tuaregs and groups fighting to impose Sharia law in northern Mali of carrying out grave rights abuses such as rape, murder and using child soldiers.
A report released on Wednesday by the London-based rights group said government soldiers had also carried out extrajudicial killings, branding the crisis Mali's worst human rights situation in 50 years.
Tuaregs fighting for the separatist Azawad Liberation Movement (MNLA) and other groups have seized control of much of the north of the country since a military coup in Bamako in March.
"After two decades of relative stability and peace, Mali is now facing its worst crisis since independence in 1960," said Gaetan Mootoo, Amnesty International's West Africa researcher.
"The entire north of the country has been taken over by armed groups who are running riot. Ten of thousands of people have fled the region, creating a humanitarian crisis in Mali and in neighbouring countries."
The Amnesty researchers collected testimony from women and girls who said they were "raped, sometimes collectively, by armed men including by members of the MNLA, particularly in Menaka and Gao".
"Delegates found evidence of the presence of child soldiers within the ranks of the armed Tuareg and Islamists groups who took control of the north of the country."
The report states that soldiers too, were guilty of human rights violations.
"Malian soldiers beat and then extra-judicially executed three unarmed people accused of spying for the MNLA in Sevare [630km north of Bamako] on 18 April 2012," read a statement from Amnesty.
The armed groups have also tortured and abused captured soldiers, slitting their throats, according to testimony from other soldiers who were taken prisoner and later released.
One group, Ansar al-Din, which has set about imposing Sharia law in the towns under its control, including the fabled Timbuktu, is using intimidation, violence and arbitrary killings to do so, according to Amnesty.
Mootoo warned that without efforts to protect human rights "the entire sub-region risks destabilisation through the effects of political instability, armed conflict in the north and the food crisis which affects the whole of the Sahel."
Amnesty urged Malian authorities and armed groups to allow United Nations and other humanitarian agencies unrestricted access to refugees and internally displaced people, particularly in northern Mali.