DAKAR (Reuters) - Congo’s government on Saturday said it had returned the body of a tribal leader whose death last year triggered a conflict in Kasai Central province that has killed more than 400 people.

The return of the body of Kamuina Nsapu - the leader of a tribal militia by the same name - has been one of its key demands during a brutal conflict that started last July and worsened when Congolese forces killed Nsapu the following month.

In a statement, interior ministry spokesman Louis d’Or Balekalayi also said the government would recognize his successor Jacques Kabeya Ntumba as a customary chief. Failure to do this for Ntumba’s predecessor was one cause of the uprising.

The fighting in Kasai has become the most serious threat to President Joseph Kabila, whose decision to stay in power even though his mandate ran out in December has stoked rebellion and lawlessness in different parts of the Democratic Republic of Congo.

“His body was left with the family who buried him in his village on the same day,” the statement said. “The family solemnly declared the end of the war, specifying that anyone who continues to do criminal or terrorist acts does not represent them.”

It was not immediately possible to reach the family or any of the militia’s leaders for a reaction. However, it was unclear whether this gesture by the government would sooth tensions.

Initially contained in one area, the rebellion has since spread to five of Congo’s 26 provinces. The fighters operating under the name “Kamuina Nsapu” appear to do so independently and without a clear leadership structure, and some recent violence appears to have degenerated into ethnic score-settling.

Many of the dead have been dumped in mass graves, a violation of local customs.

Analysts fear growing violence in Congo could spark a repeat of the conflicts between 1996-2003, mostly in the east, in which millions died, mainly from hunger and disease. Dozens of armed groups continue to fight over natural resources and prey on the civilian population.

Two U.N. officials, one a U.S. citizen and one Swedish, were kidnapped and killed by unknown assailants in Kasai-Central last month. Four Congolese accompanying them were also kidnapped, but their bodies have not been found.

Congolese authorities said on Friday they had arrested two people suspected of involvement, but one of the prisoners has escaped.