Ethnic Tuareg separatists in Mali called on the International Criminal Court on Tuesday to launch an investigation into alleged atrocities committed by soldiers during the conflict in the west African nation.

"Soldiers have engaged in acts of torture, summary executions and forced disappearances" in several areas including Timbuktu and Gao, the Azawad National Liberation Movement (MNLA) said in a statement.

The movement said its lawyers have asked the International Criminal Court in The Hague to open an investigation "into crimes committed by the Malian army against members of ethnic groups (such as) Fula, Tuareg, Arab and Songhai".

In January, ICC chief prosecutor Fatou Bensouda warned Mali over reports that the army had committed abuses after a rights group accused Malian soldiers of carrying out a string of summary executions since the French-backed offensive against Islamist extremists began on January 11.

Bensouda urged the Malian authorities to "investigate and prosecute those responsible for the alleged crimes".

Rights groups say the army has targeted people accused of collaborating with the Islamists, in particular the lighter-skinned Tuareg and Arab ethnic groups.

The ICC in January opened a probe into crimes committed by "armed groups" since January 2012 in the troubled nation, once one of the region's few democratic success stories.

Al-Qaeda-linked Islamist groups last year took advantage of a coup in Bamako and a rebellion by ethnic Tuareg separatists in the north to seize control of the vast desert area.

The MNLA initially allied with the Islamist groups but soon found itself sidelined as an extreme form of Islamic law was imposed across an area larger than France.

Considerably weakened, the movement began peace negotiations with the Malian authorities in December and dropped its demand for independence in favour of a request for self-rule.

Last month, Malian judicial authorities issued arrest warrants for MNLA leaders, accusing them of "terrorism" and "sedition".

Mali ratified the ICC's founding document, the Rome Statute, in 2000.