An attack by tribesmen near a makeshift camp for displaced people in Sudan's conflict-hit North Darfur state killed six civilians including two children, a resident and a UN official said Tuesday.
Monday's attack came just hours after a senior international mediator working on resolving the conflict said the region was now "stable".
A peacekeeper from the UN-African Union Mission in Darfur was also wounded in the attack near the makeshift camp in Sortoni where tens of thousands of people have taken refuge from an upsurge in fighting this year between the army and ethnic minority rebels.
The UN Humanitarian Coordinator in Sudan, Marta Ruedas, "condemns the reported shooting and killing of six civilians, including two children, by armed local tribes in Sortoni", a statement said.
Asked about the attack, Tijani Sissi who heads the Darfur Regional Authority said he was unaware of the latest violence.
Insisting that the region was secure, he said that "there are some isolated incidents still occurring".
"But this is normal as the region is coming out of a war," Sissi told reporters.
A resident of the makeshift camp told AFP that gunmen on camels and in pick-up trucks attacked twice using rocket-propelled grenades and machineguns.
The UN Office for the Coordination of Humanitarian Affairs said the incident followed a "reported rise in tensions between displaced people and armed tribesmen over cattle raiding".
Cattle rustling is a frequent source of conflict in Darfur. Last month, as many as 20 people died in clashes between two rival Arab tribes in East Darfur sparked by livestock thefts.
Darfur has been gripped by conflict since 2003, when ethnic minority rebels rose up against President Omar al-Bashir, complaining that his Arab-dominated government was marginalising the region.
Bashir launched a brutal counter-insurgency and at least 300,000 people have been killed in the conflict, the United Nations says. Another 2.5 million people have fled their homes.
Bashir is wanted by the International Criminal Court on war crimes charges related to Darfur, which he denies.
Since 2003, parts of Darfur have been further destabilised by conflicts between the region's myriad ethnic and tribal groups, as well as rising criminality.
The UN's independent expert on human rights in Sudan, Aristide Nononsi, said after visiting Darfur late last month that security in the region remained "fluid and unpredictable".
However, Qatari deputy premier Ahmed bin Abdullah al-Mahmud, who is mediating between the warring parties, said the region was now stable.
"We visited Darfur so many times... Darfur is now stable," he told reporters in Khartoum on Monday.
The Sudan government says an April 11-13 referendum which produced a majority for retaining five states in Darfur rather than the single region long demanded by the rebels turned the page on the conflict.
The rebels boycotted the vote, calling it unfair.