The world body's refugee agency, the UNHCR, said the dead -- five more than it initially reported on Thursday -- were all men. It quoted witnesses as saying one had been dragged to his death behind a horse.
The attack on the Aro Sharow camp on Wednesday, the first reported on a centre for internally displaced people in Darfur, involved 250-300 armed Arab men on horses and camels, the UNHCR said.
It said an agency team on the ground had established that 17 camp residents had been killed and 17 others from nearby villages who had been in the area for market day.
The raiders also stole cattle and burned down the flimsy shelters that house between 4,000 and 5,000 people.
Fighting erupted in Darfur in early 2003 when rebels took up arms over what they saw as Khartoum's preferential treatment of Arab tribes. They accused the government of backing militias that have driven non-Arabs from their villages.
Tens of thousands have been killed and more than 2 million people are living in the camps, mostly inside Darfur, which is the size of France.
Clashes have continued in Darfur despite the rebels and Khartoum signing a ceasefire. Little progress has been made in peace talks.
High Commissioner for Refugees Antonio Guterres said on Thursday it was the responsibility of the Sudanese government to restore order.