"We have reached an impasse, because when we opened these negotiations we did not realize that the U.S. demands would so deeply affect Iraqi sovereignty and that is something we can never accept," Maliki told Jordanian newspaper editors during a visit to Amman.

Iraq and the United States have since March been secretly negotiating a security and strategic agreement that would provide a long-term legal basis for the continued U.S. military presence in the country after the Dec. 31 expiry of the U.N. mandate, which defines its current status.

"We can't extend the U.S. forces permission to arrest Iraqis or to undertake the responsibility of fighting terrorism in an independent way, or to keep Iraqi skies and waters open for themselves whenever they want," Maliki said in his first detailed comments on the negotiations.

"One of the important issues that the U.S. is asking for is immunity for its soldiers and those contracting with it. We reject this totally," he added.

President Bush and Maliki announced in November they aimed to finalize the framework agreement by the end of July, in the hope of being endorsed by the Iraqi cabinet and 275-member parliament before year's end.

But Iraqi officials have this month voiced opposition to the U.S. draft proposals, saying the Americans were seeking to overstep Iraqi sovereignty and consolidate their occupation, implying that an agreement would unlikely be reached before the U.S. presidential elections and the next administration takes office.

Iraqi sources in Amman told the Middle East Times that Maliki assured leaders of the large Iraqi community in the Jordanian capital that his government would not accept a pact that in any way threatens Iraqi sovereignty.

The sources said Maliki told them in a meeting in Amman that the government has turned down four U.S. drafts proposed since March, adding it will take time before arriving at an agreement which would not cement U.S. presence, and getting it endorsed through parliament.

The Iraqi prime minister's remarks sharply contrasted with Bush's insistence, during a visit to Germany this week, that he was confident that differences would be ironed out and at reaching a strategic deal with Iraq.

Iraqi lawmakers have said they were facing U.S. pressure to meet deadlines on core issues regarding the status of their country that should take months to negotiate, particularly as the country is still in a state of war and with the large presence of the 150,000-strong U.S. troops currently there.

Last week, a majority of Iraq's parliament wrote to the U.S. Congress rejecting a long-term pact with America if it excludes a commitment to withdraw U.S. forces.

"The majority of Iraqi representatives strongly reject any military-security, economic, commercial, agricultural, investment or political agreement with the United States that is not linked to clear mechanisms obligating the occupying American military forces to fully withdraw from Iraq," the letter to Congress said.

Iraqi lawmakers said Baghdad had turned down two U.S. drafts this week alone, after a "toned-down version" with ambiguous wording allows the U.S. military free access to Iraqi bases and fails to set a time limit.

U.S. officials have insisted that Washington was not seeking "permanent bases" nor planning to use Iraq as a launching pad to attack neighboring countries, such as Iran and Syria.

Sources close to the negotiations have revealed that the rejected U.S. drafts on using Iraqi military bases excluded a time limit on access to the bases to "conduct military operations in Iraq and to detain individuals when necessary for imperative reasons of security." The authorization for these operations was identified as "temporary."

On immunity from prosecution in Iraqi courts, the latest draft dropped the protection of civilian security contractors and confined immunity to U.S. military personnel only.

Iraqis strongly oppose the presence of tens of thousands of foreign private security contractors, after last year's killing of 17 Iraqis in Baghdad by Blackwater, a U.S. firm protecting American officials in Iraq.

Lawmakers, however, are also opposing immunity for U.S. troops and have vowed not to sign any deal that would protect the soldiers from suspected war crimes.

While the negotiations will continue until an agreement is reached, Iraqi officials have in any case made it clear they will not rush into accepting a long-term agreement to meet political deadlines in Washington, especially if the text does not provide clear wording that safeguards Iraqi sovereignty, and thus an end to the occupation.

In a related development Friday, Iraq's Shiite maverick cleric Moqtada Sadr declared he plans to form a new armed group to fight U.S. forces in Iraq.

"The resistance will be carried out exclusively by a special group which I will announce later," Sadr said in a statement read out at a mosque in the Iraqi Shiite town of Kufa. "We will keep resisting the occupier until liberation or martyrdom."