The surrender of Iraqi forces to advancing U.S.-led coalition troops appears to be gathering momentum.

A senior Pentagon official says the commander and deputy commander of one of Iraq's regular infantry divisions have surrendered to allied forces in southern Iraq.

The official had no firm word on how many soldiers of the 51st division surrendered with them. But he indicates most of the division, perhaps as many as 15,000 men strong, had already deserted in the face of the coalition ground advance.

It is but one example of what many Pentagon officials see as the steady collapse of Iraqi leader Saddam Hussein's support base.

"Certainly, many Iraqi military are heeding our message that it is better to fight for the future of Iraq than to fight for Saddam Hussein," said General Richard Myers, Chairman of the U.S. military's Joint Chiefs of Staff.

Still, coalition troops are encountering scattered armed resistance in their advance towards Baghdad. General Myers says they should not get too comfortable because, as he puts it, there are many unknowns out there.