"Civilians in villages in North Darfur are forced to flee due to indiscriminate aerial bombardment by government aircraft waging a military campaign against rebel groups," Jose Diaz, spokesman for UN human rights chief Louise Arbour, said in Geneva on Friday.
Diaz, citing clashes in the locality of Tabarat that led some 400 people to arrive recently in a Darfur camp, said "the military campaign against rebel movements in North Darfur that have not signed on to the peace agreement continued through the first two weeks of September".
He said the government attacks were causing more people to be uprooted from their homes and an increase in civilian casualties, but did not provide any figures for civilians recently killed or wounded by the fighting.
At least 200,000 people have died and more than two million people have been displaced in the Darfur conflict, which began in early 2003 when ethnic African tribes revolted against the Khartoum government. The government is accused of unleashing Arab militiamen blamed for rapes and killings.
Despite a May peace agreement, aid workers and rights groups say the violence has increased in recent months.
Sudanese government forces on August 28 launched a major offensive believed to involve thousands of troops backed by bomber aircraft and helicopter gunships in a bid to flush out rebel strongholds in the troubled western region.
African Union troops have failed
to stop the violence in Darfur
Diaz cited reports from UN monitors in Sudan in making the accusations against Khartoum.
He said some of the air strikes have reportedly been carried out by forces dropping bombs from the back of a white plane - appearing to corroborate a claim made earlier this month by Human Rights Watch that the government was indiscriminately attacking villages.
Amid the violence and death in Darfur, Diaz said the conviction two weeks ago of a soldier in North Darfur for raping an 11-year-old girl was a positive note. The soldier was sentenced by a court in Kabkabiya to five years in prison.
"The court heard testimony from the victim, a child witness, and an adult, and considered a medical report that confirmed the victim was raped," Diaz said.
"The conviction shows that there can be action to stem sexual violence when there is the required will."
UN human rights reports have criticised authorities in Sudan for failing to punish acts of sexual violence committed in Darfur.
Diaz said women remain vulnerable to attack by militia members when leaving towns or camps for displaced people. Human rights monitors have warned of a recent increase in rape cases in the region.