The US Secretary of State, Mr Colin Powell has said Iraqi leaders will have six months to draft a new constitution for their nation.
In a New York Timesinterview Mr Powell said only then would the US transfer authority back from the occupying force.
The new constitution would pave the way for a new form of government and leadership based on either a presidential or parliamentary system by next year, Mr Powell said.
He said: "We would like to put a deadline on them. They've got six months. It'll be a difficult deadline to meet, but we've got to get them going."
His comments came amid growing pressure from France for a swift return of sovereignty from the US-led provisional administration to the Iraqi people.
The move was also seen as an attempt to win support for a new United Nations Security Council resolution which would enable more countries to send extra troops and money to help secure and rebuild Iraq.
Western diplomatic sources have said that such a new UN resolution could be completed by next week.
In a fresh sign of the ongoing security problems in Iraq, the UN pulled most of its 86 foreign workers back into Jordan Thursday.
UN Secretary General Mr Kofi Annan made the order in the wake of a second bombing at its Baghdad headquarters.
In the interview Mr Powell also warned that Saddam loyalists, and members of the ousted Baath party, could attack an Iraqi government they considered to be illegitimate.
He warned against a French plan to transfer authority back to Iraqis in a matter of months, saying such an unelected leadership would be an even bigger target for pro-Saddam elements.
"They would go after an illegitimate government that does not enjoy the will of the people, just as easily as they would go after us," he said.
PA