But Iraq's largest Shiite Muslim opposition group has announced it will not attend while Ahmad Chalabi, who heads the Iraqi National Congress and has been tipped as a future leader, is sending a representative in his place.

The controversy comes as the United States faces mounting calls to speed up the transitional process, even though it has said the war launched March 20 to topple Saddam's regime is not yet over.

The list of invitees has not been made public and the meeting is being held in extremely high security on an air base under US control in southern Iraq near the town of Nasiriyah.

The US delegation will be led by Zalmay Khalilzad, the White House special representative to the Iraqi opposition.

The Supreme Assembly of Islamic Revolution in Iraq (SAIRI), whose headquarters being in neighbouring Iran was a source of tension between Tehran and Saddam's Baghdad regime, said late Monday it was snubbing the meeting.

"We refuse to put ourselves under the thumb of the Americans or any other country, because that is not in the Iraqis' interests," said Abdul Aziz al-Hakim, the group's number two.

"We have been told that the aim of the meeting is to discuss setting up a government and not actually setting it up. What we badly need is a provisional Iraqi government."

SAIRI is the largest opposition group representing Shiite Muslims, the majority population in Iraq which was dominated in the Saddam era by the Sunni Muslim minority.

Chalabi was sending a representative even though he has headquarters little more than a stone's throw from the site of the meeting.

Amid extensive scepticism about US plans for remaking the country, Chalabi -- who has lived in exile most of his life -- has backing from only parts of the US administration and remains an unknown quantity for most Iraqis.

SPACE.WIRE