Their statement came shortly after Sunni negotiators offered their own proposals on the deal-breaking issues of federalism and the fate of former ruling party members as U.S. diplomats worked furiously to mediate a deal on the eve of a parliament session to sign off on the draft.

U.S. officials pressed the Shiite Muslim, Kurdish and Sunni Arab delegations to reach a consensus so the National Assembly can be presented a document acceptable to all - enhancing chances for easy approval by voters in an Oct. 15 referendum.

Shiite and Kurd leaders already accepted the draft, but parliamentary approval over objections by the Sunni minority would be a severe blow to President Bush's hopes that a new constitution will lure Sunnis from the insurgency and hasten the day U.S. troops can go home.

There was no comment on the new Sunni proposals from Shiites and Kurds, who said compromises on federalism and purging Baath Party members that they submitted Friday were their final offers. Sunni negotiators said Saturday that those revisions were unacceptable.

U.S. Ambassador Zalmay Khalilzad met with various negotiators and parliament's Sunni speaker, Hajim al-Hassani, late Saturday trying to broker wording acceptable to the Sunnis.

But prospects for a compromise dimmed when four Sunni Arab members of the Cabinet and a Sunni deputy prime minister declared that they objected to 13 provisions in the draft - more points than Sunni negotiators cited in talks Friday.

Among other things, the five Sunnis objected to measures reserving government posts for members of specific religious groups, demanded postponement of any decision on federalism, wanted all references to Saddam Hussein's Baath Party removed and insisted the constitution identify Iraq as an Arab - and not just an Islamic - country.

The statement was issued by Culture Minister Nouri Farhan al-Rawi, Minister of State for Women's Affairs Azhar Abdel-Karim, Minister of State for Provincial Affairs Saad al-Hardan, Industry Minister Osama al-Najafi and Deputy Prime Minister Abed Mutlaq al-Jbouri.

Although the five were not directly involved in the negotiations, the statement was significant because of their stature in the community. If Sunnis of such rank find the draft objectionable, it is questionable whether supporters could sell the document to rank-and-file Sunni voters more influenced by radical clerics and vulnerable to insurgent threats.

Sunnis account for only 20 percent of Iraq's 27 million people, but they are in a strong position to derail the constitution. If two-thirds of voters in any three provinces reject the charter in the referendum, the constitution will be defeated, and Sunnis have the majority in at least four provinces.

Unless there are further changes, Sunni leaders said their people should oppose the charter peacefully by voting "no" in the referendum.

"We want you to express your point of view but without violence," said the Sunnis' chief negotiators, Saleh al-Mutlaq.

In a bid to placate Sunnis, the U.S. military announced Saturday that nearly 1,000 security detainees - virtually all believed to be Sunnis - had been released from Abu Ghraib prison the past several days. It was the largest release to date.

Iraqi police, meanwhile, said they freed an unspecified number of people arrested this week in the Madain area, 12 miles, southeast of Baghdad. Sunnis had complained the Shiite-controlled police arrested dozens of Sunnis there to keep them from enrolling to vote in the constitutional referendum before the registration deadline this Thursday.

Al-Hassani, the parliament speaker, said he planned to convene the legislature Sunday, a workday here, but no hour was announced. It was unclear whether the draft constitution would be put to a vote in the assembly, where Shiites and Kurds hold 221 of the 275 seats.

The speaker said Shiites and Kurds sought to address Sunni concerns by offering Friday to put off consideration of federalism's details until after a new parliament is elected in December, when Sunnis are expected to expand on the 17 seats they won Jan. 30 after many Sunnis boycotted that vote.

Shiites and Kurds also acknowledged that many members of Saddam's party were not criminals and wouldn't be covered by a charter provision on purging Baathists from government and public life, al-Hassani said.

Sunni negotiator Fakhri al-Qaisi said his side saw no "essential change" in those areas and submitted their own proposed wording.

Shiite negotiator Ali al-Adeeb insisted his group offered major concessions.

"Regarding the powers given to provinces, this is the right of the Iraqi people and we can give up this right," al-Adeeb said. "It could be regulated by the next National Assembly ... As for the Baath issue, there were crimes and there should be punishment for the criminals. This is a right of Iraqis that we cannot give up."

Opponents of the constitution within both the Sunni and Shiite communities rejected the draft even before it was finalized. An alliance including the Sunnis' Association of Muslim Scholars and the movement of radical Shiite cleric Muqtada al-Sadr condemned a "political process which had been led by occupiers and their collaborators."

"We consider this draft as a next step of this process which does not represent the peoples' will," the group declared.

Sunnis fear that federalism, demanded by Shiites and Kurds, not only would establish a giant Shiite state in the south but also encourage Kurds to try to expand their self-rule region into northern oil-producing areas. That would leave the Sunnis cut off from Iraq's oil wealth.

Sunnis resent attempts to ban former Baath Party members because they believe that would deprive them of a livelihood and prevent Iraq from using the talents of thousands of professors, senior executives and others who joined the organization to advance their careers.