"The enemy is taking what forces he can muster and is ordering them back into the city ... for a last stand," a senior American military officer told the daily late Wednesday.

"We have been trying to kill anything that is moving toward the city. We don't want a big siege at the end of this," added the unnamed officer.

However, some Iraqi units that have been protecting Baghdad to the south have managed to pull back into the city, US officials reported, adding that Iraqi troops were at key traffic intersections in the city.

US forces have been monitoring the movement of Iraq's Republican Guard units from the air, while warplanes and surface-to-surface missiles bombed their positions.

The Times quotes US military estimates indicating that between 1,000 and 2,500 Iraqi tanks have been destroyed since the war began.

The US goal is to move its troops to the entrance to Baghdad and prepare for the final battle inside the city, the daily said.

US marines pushing towards Baghdad from the southeast moved near Baghdad airport on Thursday, US military officials in Qatar told AFP.

In a separate story, the Times said the US military has stepped up its campaign to sow doubts among the Iraqis about the welfare of their President Saddam Hussein, taking advantage of his low profile lately.

"From what our intelligence is picking up, some of the Iraqi commanders themselves have not heard from him," one senior US official told the Times. "And we don't know ourselves. So you could call this psychological warfare, or you could call it exploitation of the biggest mystery out there," he added.

Another official said US President George W. Bush was "deeply intrigued" about Saddam's fate during one meeting this week.

"The consensus was that the mystery about Saddam is growing, and that could be useful to us as we head into Baghdad," said the official who attended the meeting.

SPACE.WIRE