UNITED NATIONS - Citing dangers of renewed war between Hutus and Tutsis, a senior U.N. official urged central African leaders Thursday to mete out ''justice not revenge'' against extremists responsible for a massacre.

Undersecretary-General Jean-Marie Guehenno told reporters after briefing the U.N. Security Council that threats of retaliatory action by Burundi, Congo and Rwanda following the mass killing of at least 160 refugees at a U.N. camp in Burundi could lead to renewed fighting.

''I think there is a real danger of violence, of a spiral of violence,'' Guehenno said. ''We do call on all actors at the moment to exert maximum restraint. This horrific massacre at Gatumba [camp] must not lead to a cycle of revenge. There has to be justice, not revenge.''

A decade of violence between the region's majority Hutus and minority Tutsis has wracked central Africa, including the 1994 Rwandan genocide, a continuing civil war in Burundi that started in 1993, and two invasions of Congo by Rwanda and Burundi in attempts to root out Hutu militias.

Retaliatory violence could undo peace efforts in Congo, where a 1998-2003 civil war involved fighters from five countries and left more than 3 million people dead, most through strife-induced hunger and disease.

A Burundian Hutu rebel group, the National Liberation Forces, claimed responsibility for the attack last Friday night on Gatumba, which sheltered Congolese Tutsis known as Banyamulenge who had fled fighting in their troubled country. The rebels later claimed they were searching for Burundi army supporters in the camp but Guehenno said they didn't deny involvement ''in the atrocities that were committed in Gatumba.''

Burundi and Rwanda on Tuesday threatened to send troops into neighboring Congo to hunt down the militiamen who attacked the camp from bases in eastern Congo. The Burundian army chief accused Congolese soldiers of participating in the massacre.

A renegade Congolese army commander, a Tutsi whose troops briefly seized a key city in eastern Congo last June, also threatened Tuesday to oust the ''government that slaughters its own people.'' Congo's interim government responded, saying it wanted to resolve the situation diplomatically, but was ready ''to react'' if Burundian or Rwandan troops crossed the border.

Guehenno called the threats of military action ''very dangerous'' and warned that they ''could lead to terrible disasters.''