The UN human rights chief accused authorities in the Democratic Republic of Congo Tuesday of backing a new militia behind "horrific attacks" in the Kasai provinces, including hacking and burning hundreds of civilians to death.

"I am appalled by the creation and arming of a militia, the Bana Mura, allegedly to support the authorities in fighting the Kamwina Nsapu (rebels), but which has carried out horrific attacks against civilians from the Luba and Lulua ethnic groups," Zeid Ra'ad Al Hussein told the UN Human Rights Council. 

A UN spokesman told AFP it remained unclear whether it was local or national authorities supporting the militia.