The council, led by Ayatollah Mohammed Bakr Hakim, is made up almost entirely of Shiite Muslims, who dominate in southern Iraq.
Hamid Bayati, London representative of the council, said the group was willing to participate in a new Iraqi government, but not in an interim government that is to be overseen by retired U.S. Army Lt. Gen. Jay Garner.
The U.S. goal is to hold a national conference in Baghdad, although State Department officials say that could still be at least several weeks away.
"It depends, obviously, on the military situation, on the security situation, on how quickly Iraqis are able to speak out in different places, how quickly Iraqis are able to start considering their own future in different parts of the country," Boucher said. "You can't have a national conference until people from the whole nation can attend."
The session will be presided over by White House special envoy Zalmay Khalilzad and Assistant Secretary of State Ryan Crocker.
In an indication of the continuing dispute in Washington over Ahmed Chalabi, leader of the opposition Iraqi National Congress, U.S. officials said Friday that he has not been invited to the meeting, although they expect he will show up.
Also Friday, Iraq's U.N. ambassador, Mohammed Douri, who on Wednesday had declared, "The game is over," said his final goodbyes at United Nations headquarters in New York. He said he planned to leave for Paris and then fly to Damascus, the Syrian capital, before returning home to Iraq.
Watson reported from Mosul and Perry from Baghdad. Times staff writers Jeffrey Fleishman in Kirkuk; John Daniszewski and Michael Slackman in Baghdad; Mark Porubcansky in Doha; Edwin Chen, Richard Serrano and Robin Wright in Washington; and John J. Goldman at the United Nations contributed to this report.