DR Congo's President Félix Tshisekedi said on Thursday that his troops were mounting a military response as Rwanda-backed M23 fighters advanced in the east of the country.
In his first remarks since vast swathes of the eastern DRC fell to the militants, Tshisekedi said: " A vigorous and coordinated response against these terrorists and their sponsors is underway."
He also criticised the international community for failing to act. "Your silence and inaction ... are an affront to the DRC," he said in a televised address on Wednesday night.
Tshisekedi warned that the advance of the fighters could lead to an escalation across the broader Great Lakes region. He denounced the presence of thousands of Rwandan soldiers on Congolese soil and described the M23 as a "puppet".
The M23 armed group, backed by some 3,000 to 4,000 Rwandan soldiers, according to the UN, has been fighting the Congolese army in the region for more than three years.
On Sunday night, its forces entered Goma. By Wednesday, after sporadic exchanges of fire in the morning, fighting ceased as the M23 and the Rwandan army took up positions in most of the city's neighbourhoods.
Civilian toll
At least 100 people have been killed and more than 1,000 wounded, according to several hospitals. Goma's medical facilities are overwhelmed, and bodies litter the city's streets, the UN said at a press briefing on Tuesday, citing its staff on the ground.
Despite international pressure to end the crisis, Tshisekedi refused to attend crisis talks with his Rwandan counterpart Paul Kagame on Wednesday.
At a videoconference summit of the East African Community, regional heads of state called for a peaceful settlement. "The summit strongly urged the government of the DRC to directly engage with all stakeholders, including the M23 and other armed groups that have grievances," they said in a post-summit communiqué.
Angola, which mediated a failed attempt at talks last month before the M23 launched its offensive, called for the Congolese and Rwandan leaders to meet urgently in Luanda. Tshisekedi arrived there on Wednesday for talks about next steps, a statement from the Angolan presidency said.
The latest fighting has worsened an already dire humanitarian situation, causing food and water shortages and forcing half a million people from their homes this month, the UN said.
Kinshasa protests
In the capital Kinshasa, furious protesters attacked embassies on Tuesday, accusing foreign governments of failing to intervene in the crisis. Demonstrators burned tyres in the streets and looted supermarkets before authorities banned further protests. The capital remained calm on Wednesday.
The United States, whose embassy was targeted, ordered non-emergency staff and their families to leave. Belgium also warned its citizens against travelling to the DRC, while Brussels Airlines cancelled flights to Kinshasa.
The UN, US, China and European Union have all called on Rwanda to withdraw its forces from the region.
DRC is rich in gold and other minerals such as cobalt, coltan, tantalum and tin used in batteries and electronics worldwide.
Kinshasa has accused Rwanda of waging the offensive to profit from the region's mineral wealth. Rwanda has denied the accusations.
Kagame has never admitted military involvement, saying Rwanda's aim is to destroy a DRC-based armed group, the FDLR, created by former Hutu leaders who massacred Tutsis during the 1994 genocide in Rwanda.
