In less than a year, brutal violence in four central Kasai provinces has claimed more than 3,300 lives, according to a tally by the influential Roman Catholic Church, and displaced 1.3 million people.

The UN children's agency said more than 600,000 of the displaced are children.

A military court in Mbuji-Mayi acquitted one soldier but sentenced two others to 20 years in jail. Three soldiers got 15-year terms and one got a year in prison.

Two absconding soldiers were served life terms.

The violence erupted last September after the death in clashes of a tribal chieftain, known as the Kamwina Nsapu, who rebelled against the authority of President Joseph Kabila's regime in Kinshasa and its local representatives because he was not recognised by the local governor.

The killing sparked violence that has escalated, including gross violations of human rights such as extrajudicial killings, rapes, mutilations, torture and the use of child soldiers, according to rights groups and the United Nations.

The soldiers who got 15- and 20-year terms and life were sentenced for "murder".

The men were on trial for war crimes and other offences -- including murder, mutilation and cruel, inhumane and degrading treatment -- after a video surfaced that was purportedly shot in the Kasai village of Mwanza Lomba and showed uniformed men opening fire on civilians and then walking among at least 20 bodies.

The military court however dropped the war crimes charges.

Late last month, the UN Human Rights Council decided to send a team of international experts to help probe the violence.

However, the resolution specified that they should pass on conclusions to authorities in the Democratic Republic of Congo, while "perpetrators of deplorable crimes" should be accountable to the national judiciary.