Sanchez, who has served in Iraq for more than 13 months, ends his tour under the shadow of a prisoner abuse scandal that has damaged US prestige and raised troubling questions about officially sanctioned interrogation techniques.

He was expected to go to Germany as head of the army's V Corps pending the conclusion of investigations into the Abu Ghraib prison scandal.

Casey's nomination headed a list of general officer appointments released by the Pentagon, which also included the naming of a new chief of the US Strategic Command responsible for US strategic missile forces.

Bush nominated "Army General George W. Casey, Jr for reappointment to the rank of general and assignment as commander, Multi-National Forces-Iraq, Baghdad, Iraq," the notice said.

The choice of Casey, 55, currently vice chief of staff of the army, to succeed Sanchez as the top US commander in Iraq was widely expected.

With sovereignty set to be transferred to Iraqis June 30, senior Pentagon officials said last month that US Defense Secretary Donald Rumsfeld wanted Casey to replace Sanchez as soon as the new Iraqi interim government took office.

Sanchez was in charge of overseeing an investigation into the abuse of Iraqi detainees headed by Major General George Fay, but recused himself so that he could be questioned as part of the probe.

The Senate must first approve Casey's nomination.

"Our desire is to get him over there, although we don't control the time," said Larry DiRita, the Pentagon's chief spokesman.

Though virtually unknown to the public, Casey is a fast rising officer with broad experience as a commander of heavy infantry forces backed by an educational background in diplomacy and international affairs.

He inherits the likely task of leading US forces during a risk-filled political transition in Iraq in which the role of the US military is yet to be defined.

US military leaders anticipate violence will intensify after the handover of sovereignty as an assortment of adversaries seek to destabilize the new government while the United States races to train and graduate Iraqi security forces.

"We're not going to win it militarily. We are going to win it when Iraqis take ownership," General Peter Schoomaker, the army's chief of staff, told reporters earlier.

Some 828 US military personnel have died in Iraq since the US-led invasion of the country in March 2003.

Tapped to replace Casey as vice chief of staff of the army is Lieutenant General Richard Cody, who was nominated for promotion to four star rank.

Nominated for promotion to three star rank was Marine Corps Major General John F. Sattler, who was named to succeed Major General James Mattis as commanding general of the 1st Marine Expeditionary Force deployed in Iraq.

Bush also nominated Marine Corps Lieutenant General James E. Cartwright, currently with the Joint Staff, for promotion to full general and assignment as the commander United States Strategic Command.

The command is responsible for US strategic nuclear forces and a controversial missile defense system that is supposed to be fielded later this year.

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