As Annan joined Secretary of State Colin Powell on an unusually high-powered visit Wednesday, the United States called on the United Nations to impose an arms embargo and travel ban on Arab militias blamed for attacks on African villagers in Darfur.

The US draft would put the UN Security Council on record expressing "its determination to do everything possible to avoid a humanitarian catastrophe, including by taking further action if required."

Annan has raised the possibility of sending in international troops if Sudan's government can't protect its people in the vast and desolate western region. Humanitarian workers have likened the attacks to ethnic cleansing.

"I think we all have a responsibility to act urgently to deal with the situation in Darfur," Annan told Sudanese Cabinet ministers Wednesday.

"We have worked together for a long time, and I hope this time we are going to take such measures that we don't have people in camps for years to come," Annan said. "I think we should be able to make some real progress in the next 24 to 48 hours."

Powell said he had given Sudanese leaders a timetable to implement its commitments to disarm the militias, known as the Janjaweed, as well as lift restrictions on relief workers and seek a resolution to the crisis. While he did not specify any deadlines, he said: "We are talking within days and weeks."