Many ethnic groups in DR Congo rely on fishing for their livelihoods
More than 50,000 people have fled clashes between two ethnic groups in north-western Democratic Republic of Congo in recent weeks, the UN says.
Many of those fleeing are reported to be unaccompanied children, and some people have drowned trying cross a river into Republic of Congo.
The UN says at least 100 people have been killed in clashes between Lobala and Boba people in Equateur province.
The violence started last month after a dispute over fishing rights.
Local MPs have asked for more security in the region and a small number of UN peacekeepers have been deployed.
But most of the UN's force is embroiled in the entrenched conflict in DR Congo's eastern areas - where they support government troops fighting local, Rwandan and Ugandan rebels.
Rufin Mafouta, head of the office of Medecins d'Afrique group which works with the UN, said the number of refugees pouring over the border from DR Congo into the Republic of Congo had risen this week.
"There's been a massive influx in the past few days because the fighting has become far more intense," he told AFP news agency.
"We have noticed a lot of unaccompanied children who have certainly lost their parents, as well as pregnant women and elderly people."
Late last month Lobala and Boba ethnic groups engaged in clashes after they pulled out of a traditional deal over the sharing of fishing rights.
More than 100 people were killed, including 47 police officers.
Shortly afterwards about 100 men were arrested and the authorities in DR Congo announced that the problem was over.
But the BBC's Thomas Fessy, in DR Congo's capital Kinshasa, says Lobala tribesmen have now advanced southwards and are threatening other villages.
In the past three days at least 11 more people have been killed in an isolated area of Equateur.
And our correspondent says observers fear the situation could continue to deteriorate.