A senior defence official noted that Sanchez has served in Iraq for 13 months and that Army and Marine Corps division commanders all have rotated out of the country during that period.

When asked if the prisoner abuse scandal, which took place on Sanchez's watch, was the reason for considering a replacement for the general, this official said, "Absolutely not."

Pentagon spokesman Bryan Whitman refused to confirm or deny an ABC News report that Gen. George Casey, vice chief of staff of the Army, would take over as senior US military officer in Iraq.

"If we had something like that to announce, we would. Any speculation prior to an announcement would be irresponsible," Whitman said.

Sanchez became the top US general in Iraq last June.

Pentagon officials have talked about placing a four-star general as the overall commander in Iraq, in charge of "Multi-National Force Iraq" and responsible for the broad direction of US military operations. Sanchez is a three-star general.

In addition, the Pentagon wants a three-star general to head day-to-day military operations amid a continuing quest to crush the insurgency. As Sanchez's second in command, Lt. Gen. Thomas Metz serves in that capacity.

The senior defence official declined to give a time frame for when Sanchez would be replaced. "He's been there for 13 months. You have to be looking for replacements for these guys," the official said.