Iraqi Prime Minister Nuri al-Maliki said on Friday that negotiations with the United States on a long-term security pact were deadlocked because of concern the deal infringes Iraqi sovereignty.

"We have reached an impasse because when we opened these negotiations we did not realise that the US demands would so deeply affect Iraqi sovereignty and this is something we can never accept," he said in Amman.

"We cannot allow US forces to have the right to jail Iraqis or assume, alone, the responsibility of fighting against terrorism," Maliki told Jordanian newspaper editors, according to a journalist present at the meeting.

The White House, meanwhile, vowed to pursue the talks while respecting Iraq's sovereignty.

"We are not sure of the exact words he (Maliki) used, we intend to continue to work with the Iraqis on the negotiations," White House spokeswoman Dana Perino said.

"We fully respect their sovereignty -- it is, after all, what we fought for in the liberation," she said, referring to the March 2003 US-led invasion to topple Saddam Hussein.

Criticism has been rife in Iraq and in neighbouring Iran over the deal to cover the foreign military presence in Iraq when a UN mandate expires at the end of this year.

US President George W. Bush and Maliki agreed in principle last November to sign a Status of Forces Agreement (SOFA) by the end of July.

Maliki told Iraqi community leaders in Jordan that the talks were not over.

"These negotiations will continue until we find common ground that is acceptable for the Iraqi side and the other party," he said, adding that both sides were looking at "new ideas."

"The life of a nation, its future and its higher interests are at stake. And as long as there is no national consensus it will not happen," he said. "If parliament does not ratify it, it will not be."

One of the staunchest opponents of US military presence in Iraq, radical Shiite cleric Moqtada al-Sadr said in a statement on Friday he plans to form a new armed group to fight American forces.

Bush has acknowledged rifts with Baghdad. "I think we'll end up with a strategic agreement with Iraq. There's all kinds of noise in their system and our system," he said on Wednesday.

In February, Bush said the United States would seek a military presence in Iraq for "years" but pledged it would not establish permanent bases.

His administration has said any deal would be similar to more than 80 such pacts which Washington has with other nations, governing the scope of US operations and providing protection for its soldiers.

It says the pact will not specify troop levels, establish permanent bases in Iraq or tie the next president's hands.

Iraqi lawmaker Mahmud Othman said on Friday that Washington appeared to be flexible but there were some sticking points, especially the immunity being offered to American soldiers and private security guards.

"Americans are open to lift the immunity as far as the foreign security contractors are concerned but not for their soldiers," said Othman, a Kurd.

The immunity issue has been hotly debated since the killing of 17 Iraqis by guards from the US Blackwater security company in Baghdad last year.

Othman said the Iraqis also wanted the United States to offer long-term protection to Iraq from any "foreign invasion", adding that the demand was a concern for Washington's arch-foe Tehran.

More than five years after the invasion, around 150,000 US troops are still posted in the war-torn country after Bush ordered a "surge" of five extra brigades to combat escalating violence.

These brigades are now being withdrawn, with the final due home in July but the number of soldiers still in Iraq remains above the pre-surge level of close to 130,000.

burs/hc