The fate of Saddam Hussein is still unclear but US officials have started leaning slightly toward the view that the Iraqi leader is probably dead, US officials said on Friday.

US intelligence agencies have picked up communications or "chatter" by Iraqis on the periphery of Saddam's toppled government saying they believed he had died.

But officials caution that that by itself is not conclusive proof. "Those Iraqis either know that Saddam is dead or believe he is dead, but may be wrong, or are trying to feed disinformation to US authorities knowing their communications are being monitored," officials said.

"I'd say it's leaning slightly more to dead than alive," one US official told Reuters.

Officials also point to the rapid breakdown of the Iraqi government following Monday's massive airstrike on a building in Baghdad after the CIA received a tip that Saddam and his sons were inside.

A B-1 bomber dropped four 900-kg bombs on the site, demolishing the building and leaving behind a huge crater. US forces did not have access to the site immediately after the bombing so it may be difficult to determine who had died in the strike, officials say.

Officials who have looked at "the full panoply of intelligence" believe the odds are slightly more in favour of Saddam being dead, one official said on condition of anonymity.

"I have heard people talk about chatter," US Defence Secretary Donald Rumsfeld said at a Pentagon media briefing.

"I have not personally seen enough intelligence from reliable sources.. that would enable me to walk up and say that I have conviction that he's dead. I also lack conviction that he's alive," he said.

A defence official who spoke on condition of anonymity said as more time passes without any signs of Saddam, the more likely it was that he had died.

"The more time that passes, of course you lean that way, but he also has been known to hide for periods of time," the official told Reuters.

To help US forces hunt for the top Iraqi leaders, the military will distribute a deck of cards with pictures of the most wanted. Senior Iraqi leaders appear to have vanished after US forces convincingly took Baghdad this week.

In the deck of cards, it was unclear why some Iraqi officials were given higher value than others, but Saddam was clearly the trump -- pictured as the ace of spades.

"Clearly this is one game in which we will end up holding the ace of spades," one defence official said.