The former main rebel group during the Democratic Republic of Congo's civil war are to suspend their participation in the power-sharing government.
The Gatumba camp massacre has led to fears of more fighting
RCD-Goma leader Azarias Ruberwa, one of Congo's four vice-presidents, said the peace process had "broken down" and needed to be reassessed.
The transitional government was set up to end the five-year conflict.
But the massacre earlier this month of 160 Congolese refugees in Burundi prompted renewed warnings of war.
Mr Ruberwa said the decision was linked to the massacre, but some party members later announced they would continue to participate in the government.
It is the first time since the implementation of the peace process more than a year ago that one of the parties has pulled out.
The government is accused of backing the Hutu militia which claimed responsibility for the attack.
Many of the victims were Tutsi women, children and babies, who had fled fighting in southern DR Congo in June.
The leaders of Burundi and Rwanda threatened to retaliate and the United Nations urged all parties to show "maximum restraint".
Rwanda, which has close ties to RCD-Goma, and Burundi have already invaded DR Congo in the past, in search of the Hutu rebels blamed for killing thousands of Tutsis in the last decade.
Violence between the majority Hutu tribe and the minority Tutsis has afflicted the Great Lakes region of central Africa for over a decade.
The genocide in Rwanda in 1994 and subsequent wars in Burundi and DR Congo have stemmed from it.