President George Bush ordered U.S. economic sanctions on 31 Sudanese firms in an effort to press the Khartoum regime to stop fighting in Darfour. Officials said the firms included those that supply Sudan's military and security forces.

"I promise this to the people of Darfour," Bush said, "the United States will not avert our eyes from a crisis that challenges the conscience of the world."

All but one of the Sudanese companies were identified as being directly controlled by Khartoum. Officials said the exception, Azza Air Transport, was alleged to have shipped weapons to Darfour.

"Azza Air Transport Company has also been sanctioned under Executive Order 13400 for transferring small arms, ammunition and artillery to Sudanese government forces and Janjaweed militia in Darfour," the Treasury Department said on Tuesday.

The Treasury also cited Giad Industrial City on the new U.S. sanctions list. Giad was said to have supplied armored vehicles to Khartoum for military operations in Darfour.

Sanctions were also imposed on Sudanese military intelligence chief Awad Ibn Auf. Rebel leader Khalil Ibrahim, who refused to sign a peace accord on Darfour, was also placed on the U.S. sanctions list.

"Even in the face of sanctions, these individuals have continued to play direct roles in the terrible atrocities of Darfour," Treasury Secretary Henry Paulson said. "We are working to call attention to their horrific acts and further isolate them from the international community."

Officials said the administration wants the United Nations Security Council to impose sanctions that would block Chinese and other arms shipments to Khartoum. The proposed sanctions would also ban Sudan's military from offensive operations in Darfour.

"It will prohibit the Sudanese government from conducting any offensive military flights over Darfour," Bush said. "It will strengthen our ability to monitor and report any violations."