The US on Thursday offered a reward of US$25 million for information that leads to the capture of former Iraqi president Saddam Hussein or proves that he is dead.
A further US$15 million will be available for information that leads to the capture of either of the former Iraqi dictator's sons, Uday and Qusay.
Paul Bremer, the chief administrator in Iraq, announced the reward on the US-funded Iraqi Media Network radio. In a prepared statement, Bremer said that Saddam and his sons were "among the most evil men the world has known."
"They may or may not still be alive, but I recognize that until we know for sure, their names will continue to cast a shadow of fear over this country," he said. He urged Iraqis with relevant information to give it to "any coalition official, civilian or military."
It is the first time that a price has been put on Saddam's head. A similar bounty has already been offered for the capture of Osama bin Laden.
A allied official stressed that the ransom would come from US rather than Iraqi coffers.
The last reported sighting of Saddam alive was in the final days of the war, in the Azamiyah area of north-eastern Baghdad. During the war, US forces ordered a number of air strikes against him, but their effectiveness remains in doubt.
The search for Saddam and his two sons, who have not been seen since Baghdad fell on April 9, was said to have moved up a gear after the arrest of his secretary, national security adviser and senior bodyguard, Abid Hamid Mahmoud al-Tikriti, three weeks ago.
Mahmoud was reported to have told US investigators that Saddam and his sons survived, and that he was in hiding north of Baghdad.
The trail now appears to have gone cold.
There has been a series of increasingly audacious attacks on US and British forces in Iraq, but a senior official in the provisional authority denied that the bounty was an act of political desperation.
"In the immediate aftermath of the conflict, Iraqis were nervous," he said. "But as each day passes, more and more Iraqis are realizing that he's not coming back. They want to be on the right side of history.
"Somebody out there knows something, and I think they will come forward. The number of places Saddam has to hide are decreasing by the day."
US officials have regularly blamed former Saddam loyalists and remnants of the old regime for using the uncertainty over the former dictator's fate to intimidate Iraqis and destabilize the country.
"I have no doubt that determining the fate of Saddam Hussein would help us in our reconstruction efforts in Iraq, not least since he was responsible for so much of the damage inflicted on this country," Bremer said in his address.
Lieutenant General Ricardo Sanchez, who commands US forces in Iraq, said yesterday there had been an average of 13 attacks a day on coalition forces in the last 45 days. A total of 25 US and British soldiers had been killed in hostile action and 177 wounded, he told a news conference in Baghdad.
Sabotage attacks have become increasingly sophisticated, targeting key parts of the infrastructure such as oil pipelines and the power grid. Iraqi citizens working to help the reconstruction effort have also been targeted.