The camp, just north of Goma, had seen an influx of 30,000 people over the past three days joining the 15,000 already there, after the NCDP launched a major offensive in the North Kivu region.
Members of the UN's largest peacekeeping force, Monuc, had increased its intervention, using helicopter gunships for two days in an attempt to stop Nkunda, who says he is fighting to protect ethnic Tutsis, from advancing.
Redmond said that UNHCR staff had beendelivering food and emergency supplies to the "exhausted and traumatised" refugees when government forces were seen moving south "fairly fast, and in fairly large numbers".
Julien Paluku, the city's governor, said: "People are stampeding and the city is panicking."
Redmond told Al Jazeera that the prospect of violence akin to the Rwandan genocide was unlikely.
"I don't think we are approaching anything on that scale, but we are increasingly concerned about this situation," he said.
"Unfortunately it is the poorest of the poor who are the real victims in this conflict. If we are not able to help them, no one will, and that is what is so heartbreaking about this situation."
Ban Ki-moon, the UN secretary-general, said that the violence in the DRC is creating a "humanitarian catastrophe".
"The intensification and expansion of the conflict is creating a humanitarian crisis of catastrophic dimensions and threatens dire consequences on a regional scale," he said.
Ban also urged "all parties to immediately cease hostilities and to respect international humanitarian law".
|Monuc has been accused of failing to stop the anti-government advance towards Goma [AFP]
The fighting had started on Sunday and by Tuesday, Nkunda's men claimed to have taken a town near Goma.
Further fighting was reported on Wednesday as government forces traded heavy weapons fire with the renegade militia as they geared up for an assault on Goma.
Clashes were reported in Kibumba, about 30km north of Goma, where the UN aircraft fired on NCDP positions, temporarily stalling their advance and forcing them to retreat to higher ground.
A senior aide to Nkunda told AFP that the CNDP would take Goma.
Government forces had been blocking roads into Goma from the north, but have pulled out in disarray from a second position further north.
The Kinshasa government accuses neighbouring Rwanda of supporting Nkunda, a charge Kigali has denied.
Nkunda's troops were "backed by Rwandan tanks which are pounding our positions from border hill positions," a government official said.
Rwanda's Tutsi-led government has repeatedly denied DR Congo's accusations that it has sent troops across the border.
The UN Security Council failed to reach a decision on an urgent request to reinforce UN peacekeeping troops in eastern Democratic Republic Congo (DRC) early on Wednesday.
Alain Le Roy, the head of UN peacekeeping, briefed the council on the deteriorating situation and said that his request for additional forces had "been heard clearly by all member states".
He said that Joseph Kabila, the president of DR Congo, also made a request for a "multinational force" to support Monuc.
But the 15-member council issued only a non-binding statement in which members expressed "great concern at the resurgence of violence in eastern DRC and strongly condemned the offensive operations".
Le Roy stressed that Monuc urgently needed a special forces unit as well as air support.
"We have seen statements by the CNDP that they want to take Goma," he said.
"This is very worrying and would be very dangerous for the stability of the region."