Civic groups in Burundi are rejecting a U.N.-appointed official as mediator in crisis talks between the government and those opposed to a third term for President Pierre Nkurunziza, saying they doubt his neutrality.

Pierre Claver Mbonimpa, a leading rights activist here, told The Associated Press Tuesday that several groups had written a joint letter to U.N. Secretary-General Ban Ki-moon expressing opposition to the mediation role of Algerian diplomat Said Djinnit.

Mbonimpa said that in meetings they had told Djinnit — the U.N. chief's special envoy for Africa's Great Lakes region — that they felt he supported a third term for Nkurunziza.

Last week about 17 opposition groups wrote Ban saying they wanted Djinnit's removal, but a spokesman for Ban said Djinnit's efforts to end Burundi's political crisis are fully supported.