The United Nations' human rights chief says 580 civilians have been killed so far this year in central Mali.

Michelle Bachelet said the security situation was deteriorating, with multiple groups carrying out the killings.

The UN says ethnic militias originally formed to protect the Fulani and Dogon communities are killing people, stealing cattle, looting granaries and burning homes.

Some civilians are abducted and forced to join the militias.

Islamist movements linked to al-Qaeda and the Islamic State group are moving into central Mali, forced down from their bases in the north.

The UN accuses the Malian military of carrying out 130 extrajudicial killings, mainly targeting members of the Fulani community.

Violence is intensifying across the Sahel. There are fears that jihadist groups are moving southwards towards West Africa's coastal states.