NEW YORK (Reuters) - Saddam Hussein's fear of internal rebellion led him to distrust his military commanders even after U.S. forces began their invasion in 2003, crippling the country's defenses, the New York Times reported in Sunday editions.

Citing a classified U.S. military report as well other documents and interviews, the Times also said that top Iraqi commanders were shocked when Saddam told them three months before the war that he had no weapons of mass destruction.

Prepared nearly a year ago, the classified military report shows that Saddam discounted the possibility of a full-scale American invasion, the Times said.

Two weeks into the war, Saddam and a small circle of aides remained convinced that the main threat came from within, leading him to deny a commander's request to blow up the Euphrates river bridge to slow the U.S. advance, the report said.

His main concern over a possible American military strike was that it might prompt the Shi'ites to take up arms against his Sunni-led government, it quoted Tariq Aziz, the former Iraqi deputy prime minister, as telling interrogators.

"He thought they (the United States) would not fight a ground war because it would be too costly" in terms of casualties, Aziz was quoted as saying.

To collect the material, U.S. military analysts questioned more than 110 Iraqi officials and military officers, sometimes posing as military historians and treating officials to lavish dinners to pry loose their secrets. Others were interrogated in a detention center at the Baghdad airport or Abu Ghraib prison, the Times reported.

The accounts, it said, were viewed as credible because they were largely consistent.

After the invasion began, Saddam continued to make crucial decisions himself, and relied on his sons for military counsel, the Times said. It said his military leaders were demoralized to learn there were no WMDs, as they were counting on stocks of poison gas or germ warfare for defense.

The report also said that Saddam put a general considered to be an incompetent drunk in charge of the elite Republican Guard because he considered him to be loyal. It said commanders were in some cases banned from communicating with other units and were unable to get maps of areas near the airport because those would have disclosed the locations of Saddam's palaces.