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Iraq's prime minister said Friday that talks with the U.S. on proposals for a long-term security pact have reached an impasse over objections that Iraq's sovereignty is at stake, but held out hope that negotiators could still reach a compromise plan.

In his strongest comments yet on the debate, Nouri al-Maliki echoed concern by Iraqi lawmakers that the U.S. proposals would give Washington too much political and military leverage on Iraqi affairs.

"The first drafts presented left us at a dead end and deadlock," he told reporters in Amman, Jordan. "So, we left these first drafts and the negotiations will continue with new ideas until the sides reach a formula that preserves Iraq's sovereignty."

The security agreement would provide a legal basis for the presence of U.S. forces in Iraq after the U.N. mandate expires at the end of this year. Failure to strike a deal would leave the future of the American military presence here to the next administration.

U.S. negotiators offered new proposals this week after Iraqi lawmakers expressed outrage over the direction of the negotiations, claiming that accepting the U.S. position would cement American military, political and economic domination of this country.

"Any agreement that infringes on Iraq's sovereignty and its components will be dismissed and will not be acceptable," he added, promising any deal would be presented to Iraq's parliament for final approval.

"It is a negotiation process that will continue until we reach a common ground that is acceptable by the Iraqi and the other sides," al-Maliki said. "So, I see no reason to be worried about the possibility that Iraq will be chained by agreements. The Iraqi politicians are aware of the importance of sovereignty."

Al-Maliki's remarks reflected deep misgivings about the deal, which also has been denounced by Tehran. The Iraqi premier, a Shiite, is close to the predominantly Shiite Iran.

But a senior government adviser, Yassin Majid, sought to temper the comments, saying a preliminary draft had been rejected but there were "some alternative ideas still on the negotiating table" that would be presented at an upcoming meeting.

The U.S. Embassy in Baghdad stressed the pact was important for Iraq's security.

"U.S. discussions with the government of Iraq on arrangements for a long-term strategic partnership and security relationship continue," embassy spokeswoman Mirembe Nantongo said. "Those discussions are based on the fundamental principal of U.S recognition of and respect for Iraq's sovereignty."

"We remain hopeful, as do our Iraqi government partners, regarding a successful conclusion to these negotiations," she added in an e-mailed statement.

The mounting criticism has raised doubt that a deal could be reached before the U.S. presidential election in November. The issue also has taken on importance among Iraq's fractured political parties as they prepare for provincial elections expected in the fall.

An aide to Iraq's pre-eminent Shiite cleric Grand Ayatollah Ali al-Sistani urged negotiators to protect the national interest during a Friday sermon in the holy city of Karbala.

"Iraq's sovereignty and economy must be protected," Ahmed al-Safi told worshippers. "The Iraqi negotiators must be up to the responsibility and should have a unified point of view."

Hundreds of followers of anti-U.S. cleric Muqtada al-Sadr also rallied against the agreement in Karbala.

And Sadrist cleric Sheik Dhia al-Shawki accused the United States of trying to cement its foothold in the Middle East, calling the agreement a dangerous project for Muslims.

"This agreement is a project of domination and control," he said during his sermon in Baghdad's Shiite stronghold of Sadr City. "The Americans are calling for it to protect their interests in the Middle East and keep security of Israel and make it the biggest power in the region."

The outrage has fueled tensions that already were high amid clashes between U.S.-Iraqi forces and Shiite militia fighters.

Al-Sadr issued a new statement Friday calling for restraint in an apparent bid to exert control over his Mahdi Army militia fighters.

The cleric, who is believed to be in Iran, said the militia will continue to resist U.S.-led forces in Iraq but fighting should be limited to a select group.

"Weapons will be in the hands of this group exclusively and will only be directed at the occupier," he said, using standard rhetoric for the American forces in Iraq in a statement read after Friday prayers in the southern city of Kufa.

He warned those who disobey will be "disowned by me."

Continued fighting despite several cease-fires called by al-Sadr has raised questions about how much control he maintains over various militia factions.

U.S. troops killed five suspected Shiite gunmen and detained two others Friday during a raid near Hillah, about 60 miles south of Baghdad, the military said.

Iraqi police spokesman Capt. Muthanna Khalid said two civilians, including a woman, also were killed and three others wounded after they were caught in the crossfire.

The U.S. military said it had no reports of civilian casualties.