More than 3 000 people have fled to Zambia in the past month to escape escalating violence in Democratic Republic of Congo (DRC), according to the United Nations.

The United Nations refugee agency (UNHCR) said in a statement on Tuesday that unrest in parts of southeastern DRC has driven more than 3 360 refugees into northern Zambia since 30 August - the largest influx of its kind in the past five years.

People "are escaping inter-ethnic clashes, as well as fighting between Congolese security forces and militia groups", Andrej Mahecic, UNHCR spokesperson, told reporters in Geneva.

Those arriving in Zambia described escaping "extreme brutality, with civilians being killed, women raped, property looted and houses set alight", he said. Most are children.

The majority of those fleeing come from the northern Katanga and Tanganyika regions.

In recent years, these areas have been the scene of multiple deadly clashes between the Pygmies and Bantus from the ethnic Luba group.

A full 60 percent of those arriving in Zambia are children, including many showing signs of malnutrition, the UNHCR said.

"Malaria, respiratory problems, dysentery and skin infections are common among the refugees, who are in urgent need of protection and life-saving support," it added.

Many of the new refugees had already been displaced inside DRC by the violence before crossing the border.

"The lack of roads and the long distances ... make it difficult to monitor the situation and provide them with assistance," said Mahecic.

The approaching rainy season is expected to worsen the plight of those on the move, he warned.

The new arrivals, who bring the number of DRC refugees and asylum seekers in Zambia to around 27 300, are mostly being taken to the Kenani transit centre in Nchelenge district, 90km from the border.

But Mahecic said some were opting to remain close to the border, waiting for their families to join them.

UNHCR was helping the Zambian government and the Zambian Red Cross to distribute hot meals and basic items like tents, plastic sheeting, mosquito nets, and hygiene kits.

Aid workers were also providing psycho-social support to survivors of sexual violence.

Due to overcrowding, UNHCR said it had begun work on a second transit facility and was helping develop a more permanent settlement for the refugees.