"He's not been around. He's not active. Therefore, he's dead, or he's incapacitated or he's healthy and he's cowering in some tunnel someplace trying to avoid being caught," Defense Secretary Donald Rumsfeld said.

The White House said it was also not sure whether Saddam was alive but spokesman Ari Fleischer warned he had "missed his chance" to go peacefully into exile. An official close to US intelligence also said Saddam's fate was unknown.

Iraqi opposition leader Ahmad Chalabi told CNN he had reports that Saddam and at least one of his sons, Qusay and Uday, had survived an air attack Monday on a Baghdad building where they were believed to be meeting.

"We have no evidence that they have been killed in that attack," Chalabi said from Nasiriyah in southern Iraq.

British newspaper The Times said that Britain's MI6 intelligence agency had told the US Central Intelligence Agency that it believed Saddam had left the building before the attack.

Chalabi, leader of the Iraqi National Congress, said his reports indicated the Saddam family were in northeast Baghdad.

Fourteen civilians were killed in Monday's attack in which a B-1 bomber dropped four 2,000-pound (900-kilo) bombs on a building where Saddam and his sons were believed to be.

Lieutenant Colonel David Lapan, a Pentagon spokesman, said he could not rule out the possibility that Saddam had escaped through an underground channel.

But asked whether the Iraqi leader may have fled to his home city of Tikrit, some 150 kilometers (90 miles) north of the capital, Lapan said: "I don't know how he could get to Tikrit, when we have forces that surround it."

Lapan said US troops have not yet begun excavations on the bombing site, nor have they begun DNA tests on the remains of those killed there. Another Pentagon official, who requested anonymity, said DNA tests would take at least two days.

The Washington Times reported Wednesday that multiple US intelligence sources saw Saddam enter a building in Baghdad on Monday and not emerge before US bombs destroyed it.

Citing unnamed government officials, the newspaper said that some analysts believe eyewitness accounts suggesting that the Iraqi dictator is dead.

One of the officials described the CIA as being "in a state of euphoria," the report said.

Chalabi said Saddam's younger son, Qusay, is known to have survived the attack.

Chalabi also questioned US and British claims that Saddam's cousin, Ali Hassan al-Majid, notorious as "Chemical Ali" for ordering poison gas attacks on Kurdish villagers in 1988, had been killed.

Chalabi said Majid was smuggled into Baghdad after being wounded in an air raid in southern Iraq last weekend.

SPACE.WIRE