A lengthy negotiating process is expected, with a goal of completing a deal by December, when a UN Security Council resolution currently governing the US presence in Iraq expires.
'No permanent bases'
Morrell did not discuss the US negotiating position, but he said the final agreement "does not seek permanent bases, will not in any way codify the number of troops that will remain in Iraq".
He also said "it will not tie the hands of a future commander-in-chief, it will not require senate ratification, but we will make every effort to keep congress apprised of progress in these talks".
Attention had previously focused on the "status of forces" agreement.
David Satterfield, the state department's co-ordinator for Iraq, told congress on Tuesday that the Bush administration plans to negotiate a so-called strategic framework document on US-Iraqi relations.
Satterfield did not offer much detail on the document but said the administration did not see it as "legally binding".
Robert Gates, the defence secretary, has said he expects the Iraqi government to agree to a longer US presence.
Some members of the US congress have objected to the talks and subsequent legal review of the US role in Iraq.
They say they have not been consulted on the decision.
Democrats say the agreement could lock the US into a long-term military presence in Iraq.
Meanwhile, on the ground there was more violence on Friday as a police station was attacked in the northern Iraqi city of Mosul.
|Iraqis buried on Friday the victims of the twin|
bombings in Baghdad's Karrada district [AFP]
An car was driven through protective barriers before the driver detonated its load of explosives outside the station's front gate, killing at least three and wounding 32, officials said.
The US military said two Iraqi police were killed and one civilian, and that 12 officers were among the wounded.
The deaths came as funerals were held for many of the 68 victims of Thursday's twin bombing in a crowded Baghdad shopping district.
The funerals were held in the primarily Shia, middle-class Baghdad neighbourhood of Karradah, where the attacks took place.
Iraqi interior ministry officials put the number of wounded people at 120 after several people died from their injuries overnight.