The U.N. human rights chief on Thursday accused the Sudanese army of looting towns and raping girls and women during attacks it carried out in West Darfur with the help of Arab militias.

The attacks on Sirba, Sileia and Abu Suruj on Feb. 8 by helicopter gunships and fixed-wing aircraft left at least 115 people dead and caused 30,000 to flee their homes, Louise Arbour, the U.N. high commissioner for human rights, said in a report.

"The scale of destruction ... suggests that the damage was a deliberate and integral part of a military strategy," the nine-page report said.

The U.N. said its concerns were ignored in discussions with the governor of West Darfur. Other government officials denied collusion between the army and janjaweed militia.

If soldiers committed rights violations, "such acts were committed by individuals and were not in pursuit of a government policy," the report quoted senior Darfur officials as saying.

Most of Abu Suruj and much of Sileia was burnt down when militia on camels and horses joined the Sudanese army in attacking the towns. Some residents were burnt alive inside their homes, including a 75-year-old blind woman and a disabled girl, the report said.

The Sudanese military has said it bombed the towns while striking at rebel forces. But Darfur rebels denied any of their fighters were present.

Eyewitnesses told U.N. experts that rapes and other acts of sexual violence were committed during and after the attacks. That has been a continuing theme of the five-year Darfur conflict.

Fighting has raged since ethnic African tribesmen took up arms in 2003, complaining of decades of neglect and discrimination by the Sudanese Arab-dominated government. Khartoum has been accused of unleashing janjaweed militia forces to commit atrocities against ethnic African communities in the fight with rebel groups. At least 200,000 people have been killed and 2.5 million displaced in the conflict.

Arbour's report said there were "strong indications" that members of the Sudanese Armed Forces, or SAF, committed rapes of women and girls in Sirba, located 50 kilometers (30 miles) north of West Darfur's capital, El Geneina. "One eyewitness reported that she witnessed four girls being escorted to an abandoned hut and raped at gunpoint by a group of soldiers belonging to the SAF," the report said.

It said armed men on camels and horses shot indiscriminately at Sirba's residents and systematically torched and looted homes. Government troops did nothing to stop the atrocities, the report added.

In Sileia and Abu Suruj, eyewitnesses told U.N. investigators that Sudanese Armed Forces also took part in the pillaging.

"I witnessed SAF and janjaweed looting houses, shops and NGO offices," an eyewitness was quoted as saying. "They would load the stolen goods in their cars and on their camels and horses and take them away."

The U.N. investigation was conducted by human rights experts belonging to the U.N.-African Union force attempting to keep order in Darfur.