Updated

A top U.N. human rights investigator Friday released a scathing report that blames the Sudanese government for atrocities against its civilians in the Darfur (search) region and says "millions of civilians" could die.

"It is beyond doubt that the Government of the Sudan is responsible for extrajudicial and summary executions of large numbers of people over the last several months in the Darfur region, as well as in the Shilook Kingdom in Upper Nile State," said Asma Jahangir (search), the U.N. investigator on executions, in a report based on a 13-day visit to the region in June.

"The current humanitarian disaster unfolding in Darfur, for which the government is largely responsible, has put millions of civilians at risk, and it is very likely that many will die in the months to come as a result of starvation and disease," she said.

Jahangir said there was "overwhelming evidence" that the killing was carried out "in a coordinated manner by the armed forces of the government and government-backed militias. They appear to be carried out in a systematic manner."

The scale of violations means they "could constitute crimes against humanity for which the government of the Sudan must bear responsibility," she said.

The United Nations has described the conflict in Darfur, which began with a rebellion early last year, as the world's worst humanitarian crisis.

Last week the U.N. Security Council (search) passed a resolution giving Sudan 30 days to curb the pro-government Arab militias blamed for the violence in Darfur or face diplomatic and economic penalties.

The militias, called the Janjaweed, have been blamed for violence that has killed 30,000 people, forced a million from their homes and left an estimated 2.2 million in urgent need of relief aid.

"I remain seriously concerned at the very slow and negligent reaction of the government toward the situation unfolding in Darfur," Jahangir said. "Such a reaction despite the huge international outcry would appear to indicate either complete disrespect for the right to life of the population of Darfur, or, at worst, complicity in the events."

She said all attacks against the civilian population must stop and that the government must disarm all militias.

The government also must assure that aid workers have complete access to people in need, Jahangir said.

In New York, U.N. spokesman Fred Eckhard said the Sudanese government and the United Nations would sign an agreement Monday outlining steps Sudan must take this month to start disarming the militias and other outlawed groups and to improve security in western Darfur.

He said the agreement reached Wednesday night by Sudanese Foreign Minister Mustafa Osman Ismail and U.N. special representative Jan Pronk "has now been finalized by the Sudanese government."

A copy of the agreement was given to U.N. Secretary-General Kofi Annan who was expected to send it to the 15 members of the U.N. Security Council. It was not made public.

"A formal copy will be signed by Mr. Pronk and the foreign minister and officially issued on Monday," Eckhard said.

But it wasn't clear whether the Sudanese Cabinet had officially approved the agreement. Officials in Khartoum said the Cabinet was expected to discuss the agreement during a meeting on Sunday.

Ismail said Thursday in Khartoum that foreign military intervention to end the Darfur crisis was unlikely. He said the government "will do our best" to meet Security Council demands to end the region's violence although he called the resolution "unfair."

His comments followed a mass state-organized protest on Wednesday to condemn the U.N. resolution.

John Danforth, the U.S. ambassador to the United Nations, said Thursday the clock was ticking for Sudan and it must show by the end of the month that it is making "a good faith effort" to comply with the council resolution.