Francois Rucogoza, a spokesman representing the March 23 rebel movement at peace talks in Uganda, said a refusal by the DRC government to sign a formal peace agreement was the same as "declaring that it is ready to resume war."
A Congolese official told Ugandan newspaper Daily Monitor on condition of anonymity that "M23 allegations are false," adding the DRC military has a right to take up defensive positions to protect civilians.
Rucogoza said this week that M23 rebels were declaring a unilateral cease-fire, saying the movement has been in favor of peace in DRC.
About 800,000 civilians were displaced by fighting that began in May when M23 started a mutiny, accusing Kinshasa of reneging on a peace deal that saw former rebels integrated into the national military.
M23 in late 2012 captured Goma, the capital of North Kivu province, but withdrew.
The U.S government and the United Nations have sanctioned M23 and a Rwandan liberation movement for abuses during the recent conflict. Rwanda last week was singled out by the U.S. government for supporting DRC rebels, an allegation the government in Kigali denies.