Animal carcasses are rotting and tens of thousands of people have sought shelter in schools and government offices in Sudan's Darfur region after violence this month, the UN said on Thursday.
About 100,000 people are newly estimated to have been displaced or severely affected across a wide area of the Jebel Amir district of North Darfur state, the United Nations humanitarian agency (OCHA) said in its weekly bulletin.
"Many of these people are living in the open in appalling conditions," OCHA said.
It was the worst recent unrest in a region where a decade-long rebellion has been compounded by inter-Arab violence, banditry and tribal fighting.
Amnesty International says Sudanese security officers were reportedly involved in the gold mining-related attacks that killed up to 200 people and led to the massive displacement.
The largest group of 65,000 newly homeless are in El Sireaf, OCHA said, citing figures from the government's Humanitarian Aid Commission.
The El Sireaf district commissioner says schools and public offices have closed "due to the large number of displaced people who have taken refuge in these buildings," OCHA reported.
In the local boys' school, 25,000 people have sought refuge while a similar number are in the girls' school, said the commissioner of the district about 250 kilometres (155 miles) northwest of state capital El Fasher.
"Many displaced people came to the area with their livestock, putting significant pressure on available grazing," OCHA reported.
"This confinement is reportedly causing animal deaths and carcasses are being left unburied posing a serious health risk."
The UN and its partners have delivered more than 600 tonnes of relief supplies including blankets and sleeping mats, and food for more than 60,000 people in El Sireaf.
"Given the large number of people affected and displaced by the conflict and their geographical dispersion, the rapid transportation of humanitarian supplies to people in need presents a big challenge," OCHA said.
The scale of the emergency is difficult to determine without a more comprehensive assessment, which North Darfur authorities have not yet permitted even though the Sudanese government asked for international help which has already cost more than $2 million, OCHA added.
Foreign aid agencies face restrictions in Darfur. The US administration's senior adviser to the region, Dane Smith, warned in December that funding for recovery of the war-ravaged area is in jeopardy unless conditions ease.
Journalists also have difficulty accessing the far-west region. Sudanese state security agents on Thursday rejected, without giving any reason, a request by AFP to go to North Darfur.
More than one million people were already living in camps for the displaced in Darfur, an area roughly the size of France, because of 10 years of conflict.
Sudan's President Omar al-Bashir is wanted by the International Criminal Court for war crimes, genocide and crimes against humanity allegedly committed in Darfur.