Congolese rebels warned President Joseph Kabila on Saturday that fighting will flare up in the east of the country if his government doesn't start talks.
"The Congolese army is preparing a final assault against us," M23 leader Bishop Jean-Marie Runiga said.
"We will have to defend ourselves."
Mr Runiga has been in Kampala, Uganda, for the past few weeks working with President Yoweri Museveni to start talks with Mr Kabila's government.
"That is why there has been a ceasefire for two months but Kinshasa does not want to negotiate or to try to find a solution to the crisis quickly."
A leaked United Nations report accuses Rwanda and Uganda of supporting the rebels and Rwandan Defence Minister General James Kabarebe of directing M23.
Mr Runiga claimed that the report is wrong and insists that M23 is Congolese-led.
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