Talks on Iraq's (search) new constitution have stalled over the role of Islam and the distribution of the country's oil wealth, negotiators said Saturday. The leadership of the country's Kurdish minority said it may drop its contentious demand for the right to secede.

In Mosul (search), U.S. troops and Iraqi police clashed with insurgents Saturday, killing three of them and seizing a car used in the kidnapping-slaying of three members of the Iraqi Islamic Party the day before, police said.

Police Brig. Gen. Saeed Ahmed al-Jbouri (search) said it was unclear if the three insurgents killed were among those who grabbed three Sunnis on Friday as they hung posters encouraging people to register and vote in the Oct. 15 referendum. The Sunnis later were killed near a mosque.

Iraqis have until Monday night to complete work on the draft constitution or else parliament must dissolve. The United States is putting intense pressure on negotiators to finish the charter, which Washington hopes will in time take the steam out of the insurgency.

Mullah Bakhtiyar, a senior official from the Patriotic Union of Kurdistan, the political party of Iraq's President Jalal Talabani, said all parties were showing flexibility in order to finish drafting the constitution.

"As for the self-determination for the Kurds, this issue did not enjoy the support of Sunnis or Shiites, and we almost gave up this demand," Bakhtiyar said.

The Kurds have enjoyed de-facto independence since 1991. If they drop their demand to guarantee the right of self-determination — a code word for eventual secession that goes beyond mere federalism — it would represent a major concession and remove an obstacle to agreement on the charter.

But a comprehensive compromise on a constitutional draft remained elusive, with the main outstanding dispute focusing on the role of Islam in the new state, pitting Kurds and secular groups against Islamist parties representing Iraq's Shiite majority.

"As for the issue of Islam's role, negotiations are still underway," Bakhtiyar told The Associated Press from the Kurdish city of Sulaimaniyah.

On Saturday, leaders of all factions continued a series of meetings in Baghdad's fortified Green Zone.

Saleh al-Mutlaq, a Sunni representative on the drafting committee, said the talks had bogged down after "deep differences" emerged. He said Shiites were demanding that the new charter explicitly state that the decrees of their religious leadership were sacred — something both the Sunnis and Kurds oppose.

Shiite lawmaker Saad Jawad Kandil said the division of Iraq's potentially vast oil revenues also remained unresolved, along with the question of whether federal units could maintain relations with foreign states.

Shiites insist that foreign affairs should be the job of the central government, while the Kurds prefer that each region have the right to maintain ties with other countries, Kandil said.

As the Monday deadline to finish the constitution approached, Sunni Arabs and some Shiites rallied in Baghdad and elsewhere Friday to protest calls for a federated state.

On Saturday, about 5,000 people gathered outside the main mosque in the western city of Ramadi to condemn the constitutional process.

In the northern oil city of Kirkuk, several hundred Arabs demonstrated against the charter, chanting, "Yes to unity! No to federalism!"

"We are against federalism (because) we believe that federalism is a step toward separation," said Arab city council member Mohammed Khalil.

In the 1980s, former President Saddam Hussein displaced thousands of Kurds from Kirkuk and replaced them with Arab settlers. The city, which the Kurds seek to incorporate into their territory, has been the scene of ethnic tensions the past two years.

According to Article 58 in the interim constitution, all Iraqis, including Kurds, displaced under Saddam's regime have the right to return to their homes or receive compensation. Political leaders appear to have agreed on implementing Article 58 before general elections are held Dec. 15.

The United States believes the key to defeating the Sunni-dominated insurgency is to encourage an inclusive political process that would prompt disaffected Sunni Arabs to lay down arms.

On Friday, a Kurdish official who participated in the negotiations said the United States was pressuring the Kurds to accept demands of Shiites and Sunnis on the role of Islam in government in order to reach agreement.

The entire process hinges on the success of the drafting committee in producing a constitution acceptable to all Iraqi communities by Monday's deadline. If parliament approves the draft, it goes to voters for ratification in October.

In recent weeks, various Sunni groups — which boycotted January's parliamentary elections — have been urging fellow Sunnis to vote in the referendum and a general election planned for December. The voter-registration deadline is Sept. 1.

The boycott left the once-dominant community with few seats in a parliament dominated by Shiites and Kurds, and reduced its influence in the political maneuvering surrounding the draft charter.

On Friday, masked gunmen killed three Sunni Arab members of the Islamic Party in front of horrified witnesses outside a Mosul mosque after grabbing them as they hung posters urging fellow Sunnis to vote in the referendum.

On Saturday, men inside a car used in the kidnappings and killings fired at a patrol of U.S. military and Iraqi police. The patrol returned fire, setting the BMW on fire and killing three men inside, al-Jbouri said.

In other developments, Ramadi police reported on Friday that U.S. warplanes bombed a house, destroying it but causing no casualties. Police Capt. Nassir Al-Alousi said the house was empty at the time.

A statement released by the U.S. military Saturday said only that Air Force F-16s and Royal Air Force GR-4s "provided close air support to coalition troops" in the area. It gave no further details.

In Baghdad, two policemen were killed in a gunfight on Saturday morning with militants near Al-Shurta tunnel in the Amiryaa neighborhood, Capt. Talib Thamir said.

Unidentified gunmen also shot and killed two civilians in the Al-Amil district, and a mortar shell exploded in the capital's Mansour neighborhood, injuring a woman, police said.