An independent U.N. human rights monitor said Friday that it is "beyond a doubt" that Sudan bears responsibility "for extrajudicial and summary executions of large numbers of people" in the country's Darfur region.

In a sharply critical 26-page report, Asma Jahangir, the United Nations' special rapporteur on extrajudicial, summary or arbitrary executions, also said that members of government-backed Arab militias responsible for some of the worst excesses have been incorporated into the Sudanese police and armed forces.

"Some of the militia leaders have been integrated into the Sudanese armed forces and given official military ranks," Jahangir wrote.

The Arab militias, known as Janjaweed, are believed to have killed as many as 50,000 black civilians in Darfur over the past 18 months and to have driven more than 1 million from their homes. The Security Council adopted a resolution July 30 warning Sudan that it could face sanctions if it failed to demonstrate a commitment to disarm, arrest and prosecute militia members within 30 days.

The violence in Darfur began in February 2003, when two black rebel groups launched an offensive against the government, citing discrimination against the region's three main black tribes. The government armed and trained local Arab militias to put down the rebellion and drive thousands of potential backers from their villages, according to U.S. officials and human rights groups.

Sudan has repeatedly denied that it supports the militias and maintains that its attempts to halt their activities have been undermined by rebel activities. Sudan's U.N. ambassador, Elfatih Erwa, was unavailable for comment.

The report's release came as the Sudanese government finalized an agreement with the United Nations to establish a series of "safe areas" in Darfur within 30 days to protect displaced civilians. Sudanese authorities are required to "provide secure routes" to the havens and immediately cease all offensive military operations against the rebels in those areas, according to the agreement.

The two-page accord, to be signed Monday in Khartoum by the United Nations' top envoy, Jan Pronk, and Sudanese Foreign Minister Mustaf Osman Ismail, notes that Sudan may not be able to fully meet the Security Council's demand to disarm the militia within 30 days. It outlined a series of actions Sudan could take to "demonstrate its commitment to comply" and escape sanctions.

The Sudanese government pledges to "identify and declare those militias over which it has influence and instruct them to cease their activities forthwith," the accord states. "They would then lay down their weapons."

Jahangir's findings, drawn from a 13-day trip to Sudan in June, echo recent reports of Sudanese complicity in Darfur atrocities by human rights organizations and the U.N. high commissioner for human rights.

Jahangir said that eyewitnesses reported the presence of mass graves in some villages and charged that government-backed militias routinely looted houses, killed unarmed civilians, raped women and visited local hospitals, where they executed the wounded. She said that it was too dangerous to verify the reports of mass graves.

While Jahangir stopped short of declaring the violence in Darfur genocide, she said, "I have to conclude that there is overwhelming evidence that extrajudicial killings of civilians in Darfur have been carried out, with some exceptions, in a coordinated manner by the armed forces of the government and government-backed militias."

Sudanese women return with water to a refugee camp in Chad. Thousands have fled the Darfur region because of militia attacks.A family waits for help in a refugee camp in Sudan. Sudan has agreed to take steps to curb the Arab militias attacking the black peoples of the Darfur region.