French anti-terror prosecutors said Monday that police had arrested the former head of a rebel group in the Democratic Republic of the Congo on charges of "complicity in crimes against humanity".

Roger Lumbala, 62, is a former opposition lawmaker who led the RCD-N party, an armed group suspected by UN investigators of carrying out extrajudicial killings, rapes and cannibalism during the country's civil war from 1998-2002.

The charges concern his actions in 2002 in the northeastern Ituri region predominantly against the Nande and Twa ethnic groups, the prosecutors told AFP.

A United Nations report published in 2003 first pointed the finger at Lumbala, who became a minister in his country's transition government between 2004 and 2005.

Lumbala, who rejects the allegations, was arrested last week following a police investigation launched in December 2016.

The French judiciary has the right to arrest and prosecute suspects in crimes against humanity cases committed abroad.

After mounting a failed presidential bid in a 2006 election, Lumbala had his lawmaker's mandate invalidated in January 2013 for repeated absence, as he was reported to have spent much time in Uganda and Rwanda.

Democratic Republic of Congo authorities accused him of "high treason" and complicity with M23 rebels, who were defeated in November 2013 after an offensive by government and UN forces.

But he was allowed to return home in 2017 after a key deal to end a political crisis in the vast African country, one of a few accused figures whose freedom or return from exile was agreed.

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