Rebel forces in eastern Congo have taken control of the town of Sake, a day after capturing the city of Goma on the Rwandan border.
The M23 rebels, widely believed to be backed by Rwanda, said they planned to "liberate" all of the Democratic Republic of Congo.
The rebels accuse the government of failing to grant them positions in the army, and salaries, in line with a peace deal that ended a previous rebellion in 2009.
The rebellion has aggravated tensions between Congo and Rwanda, which the Congolese government says is orchestrating the insurgency as a means of grabbing the east's resources, which include diamonds, gold and coltan, used in mobile phones.
Diplomats at the United Nations and regional mediators in Central Africa have been seeking to prevent an escalation of hostilities in Congo.
Congolese President Joseph Kabila and Rwandan President Paul Kagame were due to meet today after holding three-way talks with Ugandan President Yoweri Museveni late yesterday, sources in the Ugandan presidency said.
In New York, the UN Security Council unanimously adopted a resolution last night condemning the seizure of Goma.
The French government expressed frustration with UN peacekeepers, who gave up the battle for the town of one million after Congo's army retreated, saying it was "absurd" that the UN force did not protect the city.
Democratic Republic of Congo has accused neighbouring Rwanda, whose army had repeatedly intervened in Congo's conflicts during the last 15 years, of backing the rebels. Kigali denies the charge and has called for dialogue.