US Deputy Secretary of State Richard Armitage said Washington had put the final touches on a decree by the US-led Coalition Provisional Authority (CPA) granting forces immunity after next Wednesday.

"It's finished today, it's going up to Baghdad," Armitage told the Senate Armed Forces Committee.

"They want obviously (to) make sure that the new government sees it, and is not in opposition to it. There have been discussions continually about it," he said.

"The combination of the CPA Order 17 as amended and UN Security Council resolution 1546 is felt by all to give us sufficient protections," he said.

General Richard Myers, chairman of the US Joint Chiefs of Staff, said that the shield from prosecution could not be withdrawn by the interim government.

"My understanding of this issue is that the CPA orders cannot be repealed or modified until Iraq's permanent government is in place to enact legislation," Myers told the committee.

"So they stay effective through that period," which will be about six months until a new government is elected and in place).

"We feel that our forces are protected," Myers said.

There are 138,000 US troops in Iraq.