The Sudanese government is complicit in the killing of citizens in the Darfur region and is putting millions at risk, a United Nations human rights investigator said Friday.

There is "overwhelming evidence" that the killings were carried out "by the armed forces of the government and government-backed militias," a report by Pakistani lawyer Asma Jahangir said.

The armed forces, volunteers and government-backed militias "had in recent months attacked villages and summarily executed civilians, looted homes and forcibly displaced the inhabitants," said Jahangir.

An estimated 30,000 people have been killed in Darfur, more than a million displaced by the violence, and 2.2 million need aid.

"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's report is based on a 13-day visit to Darfur in June.

Critics say the fighting is the result of government support for the Janjaweed, Arab militias accused of attacking Darfur's black residents. The government has said the fighting is a dispute over land or water.

Jahangir said she met many people who believe the government "was pursuing a policy of "Arabization' of the country."

Arabs want to portray themselves as "pure" Muslims, as opposed to Muslims of African ethnicity, she said.

The United States and the UN are both pressing Sudan to stop the violence.