Announcement came after UN health agency said at least 900 people were killed in fighting between the rebels and DR Congo forces in eastern city of Goma. The Rwanda-backed rebels who seized the key city of Goma in eastern Democratic Republic of Congo announced a unilateral ceasefire in the region on Monday for humanitarian reasons, following calls for a safe corridor for aid and hundreds of thousands of displaced people.

The M23 rebels said the ceasefire would start on Tuesday. The announcement came shortly after the UN health agency said that at least 900 people were killed in last week’s fighting in Goma between the rebels and Congolese forces. The city of 2 million people is at the heart of a region home to trillions of dollars in mineral wealth and remains in rebel control. The M23 were reported to be gaining ground in other areas of eastern DRC and advancing on another provincial capital, Bukavu.

But the rebels said on Monday they did not intend to seize Bukavu, though they earlier expressed ambition to march to the country’s capital, Kinshasa, a thousand miles away. “It must be made clear that we have no intention of capturing Bukavu or other areas. However, we reiterate our commitment to protecting and defending the civilian population and our positions,” M23 rebel spokesman Lawrence Kanyuka said in a statement.

There was no immediate comment from the DRC government. The rebels’ announcement came ahead of a joint summit this week by the regional blocs for southern and eastern Africa, which have called for a ceasefire. Kenya’s President William Ruto said the presidents of DRC and Rwanda would attend. Foreign ministers from the Group of Seven advanced economies, or G7, urged parties in the conflict to return to negotiations. In a statement on Monday, they called for a “rapid, safe and unimpeded passage of humanitarian relief for civilians.”.

Congolese authorities have said they are open to talks to resolve the conflict, but that such a dialogue must be done within the context of previous peace agreements. Rwanda and the rebels have accused the DRC government of defaulting on previous agreements. The M23 rebels are backed by some 4,000 troops from neighbouring Rwanda, according to UN experts, far more than in 2012 when they first briefly captured Goma then withdrew after international pressure. They are the most potent of the more than 100 armed groups vying for control in DRC’s east, which holds vast deposits critical to much of the world’s technology.

The latest fighting forced hundreds of thousands of people who had been displaced by years of conflict to carry what remained of their belongings and flee again. Thousands poured into nearby Rwanda. The fighting in DRC has connections with a decades-long ethnic conflict. M23 says it is defending ethnic Tutsis in the DRC. Rwanda has claimed the Tutsis are being persecuted by Hutus and former militias responsible for the 1994 genocide of 800,000 Tutsis and others in Rwanda.