Sudan's president has ordered a "complete mobilization" to disarm all illegal armed groups in the western region of Darfur, including the Arab militias that have been harassing African villagers.

The office of Sudan's president, Lt. Gen. Omar Hassan Bashir, said on Saturday that all government agencies should mobilize "to control and pursue all outlaw groups, including rebels and Janjaweed. . . , disarm the outlaws and present them to justice and prevent any groups from crossing into neighboring Chad."

Janjaweed is the local word for the Arab militias blamed by Darfur rebels for much of the conflict in the region. The rebels say the government has backed the Janjaweed, but the government has repeatedly denied that.

International organizations have criticized Sudan's government for failing to control the militias, which have driven hundreds of thousands of Africans out of their villages into camps for displaced persons or into exile in Chad.

The United States threatened on Friday to impose sanctions on Sudanese officials as a way of intensifying the pressure to help ease a humanitarian crisis in Darfur.

The State Department is studying whether the militias are responsible for genocide in Sudan and whether it can impose sanctions on individual officials, spokesman Adam Ereli told reporters.

The Sudanese announcement implied it was adopting a tougher line against the Janjaweed.

Sudanese government officials have previously said it would be difficult to disarm the Arab militias as long as the two main rebel groups -- the Sudan Liberation Army and the Justice and Equality Movement -- were active in the region.

The announcement also answers complaints by the government in Chad about Janjaweed incursions into Chadian territory. A source close to Chadian President Idriss Deby said on Friday Chad's army killed 69 Janjaweed in a clash near the border on Thursday.

Lt. Gen. Omar Hassan Bashir