Irish humanitarian agency Concern has evacuated staff from two towns in the Democratic Republic of Congo where rebel groups have seized control of the eastern city of Goma.
The agency's overseas director Paul O'Brien, who has recently returned from the region, said he saw "first-hand" the targeting of civilians.
"I have seen houses being systematically burnt in various villages in Masisi in order to forcibly displace families, " said Mr O'Brien.
"I have heard small arms fire including rocket propelled grenades on two successive days and nights and have witnessed families — mostly women and children — moving in various locations to escape from one armed group or another.
The agency, which has been working in the North Kivu and Katanga provinces since 1994, had approximately 45 local and international staff from the towns of Masisi and Goma in eastern DRC.
"We have evacuated Concern's staff for their own safety, but this in turn means they cannot help the people affected by this crisis," Mr O'Brien said.
"Parties to the conflict are reminded of their duty not to target the civilian population while at the same time ensuring those in need have access to humanitarian assistance."
French foreign minister Laurent Fabius called today for a review of the United Nations' peacekeeping mandate in the DRC, after rebels widely believed to be backed by Rwanda seized Goma.
Mr Fabius said it was "absurd" that a few hundred rebels had been able to parade past a UN-mandated peacekeeping force (Monusco), which gave up the battle for the frontier city of one million people.
"Monusco is 17,000 soldiers, but sadly it was not in a position to prevent what happened. It is necessary that the Monusco mandate is reviewed," Mr Fabius told reporters.
Fighters from the M23 rebel group entered Goma today after days of clashes with UN-backed Congolese soldiers that have forced tens of thousands of residents to flee the area.
A UN source said international peacekeepers gave up defending Goma after the Congolese troops left, allowing rebels to enter the city. Mr Fabius said UN secretary-general Ban Ki-moon's chief of staff would be travelling to the region in the coming days to see what could be done about the situation.
The UN mission has some 17,600 troops but the force is stretched thinly across a nation the size of Western Europe and has struggled to fulfill its mandate of protecting civilians.
Congo has already called for the mandate to be extended, to cover monitoring and protecting of the border with Rwanda, as well as eradicating rebel forces.
