Police fired tear gas to disperse demonstrators in Congo's eastern city of Goma on Wednesday who were calling on authorities to enforce an agreed withdrawal of M23 rebels from occupied territory in the region.
Regional leaders brokered a ceasefire in November under which the Tutsi-led group, which launched a fresh offensive last year, was meant to pull out of recently captured positions. The deadline for this was Jan. 15, according to Congo's presidency.
But the M23 has been accused of flouting the deal and occupying territory elsewhere to compensate for withdrawals that critics consider to be mainly ceremonial. President Felix Tshisekedi made similar accusations on Tuesday.
Christophe Lutundula, Congo's minister of foreign affairs, reiterated the accusations in a statement on Wednesday, saying M23 was still controlling access to the outskirts of Kibumba and Rumangabo, two towns they were supposed to have withdrawn from.
The M23 have denied this and accused Congolese authorities of breaching the agreement.
The M23 is a militia that claims to defend the interests of Congolese Tutsis, the ethnic group that was targeted in the Rwandan genocide. They captured Goma in 2012 before Congolese and United Nations (UN) forces chased them into Rwanda and Uganda the following year. The latest resurgence follows frustration over the slow demobilisation process to reintegrate them into civilian life if they lay down their weapons.
Civil society groups organized protests in Goma on Wednesday to denounce delays in implementing the M23 withdrawal.
City authorities banned the march but hundreds still took part, chanting and holding signs denouncing the East African Community (EAC), which set up a regional military force last year to end rebel-driven unrest.
"We are asking EAC forces to leave the city and wage offensives where the M23 is," said protester Gloire Bagaya, 26.
"They should either go home or go the front line against the enemy."
Police fired tear gas at the demonstrators and arrested about a dozen people, including three journalists, according to a Reuters reporter on the scene.
A local police commander denied any arrests were made.
The EAC regional force said in a statement that civil society groups have a right to demand immediate peace in eastern Congo, and understands the impatience.
"It is crucial to understand that the search for lasting peace demands patience for approaches put in place by the regional force to work," it said.
The M23's latest offensive has displaced at least 450,000 people and sparked a diplomatic crisis between Congo and neighbouring Rwanda.
Congo accuses Rwanda of fuelling the conflict by supporting the rebels - an accusation levelled also by Western powers and United Nations experts. Rwanda denies this.
Several protests have taken place in Goma over the past months, the latest directed at Rwanda and the ceasefire deal.
Complaints that United Nations peacekeepers have failed to protect civilians against long-standing militia violence spurred deadly protests in July.
(Reporting by Djaffar Al KatantyAdditional reporting by Sonia RolleyWriting by Sofia ChristensenEditing by Mark Heinrich and Josie Kao)
