BAGHDAD, Iraq - The Iraqi government today released the chief negotiator for the city of Fallujah in a gesture apparently aimed at reviving peace talks to end the standoff in Iraq's major insurgent bastion.

In Baghdad, a car bomb exploded late Sunday near a police patrol in the fashionable Jadiriyah district, killing at least six people, including three police officers, and wounding 26 others.

The attack came a day after insurgents ambushed and killed nine Iraqi policemen as they returned home from a training course in Jordan.

Meanwhile, Iraqi officials said a cash-for-weapons program for Shiite fighters in Baghdad's Sadr City and other locations was extended another two days until Tuesday.

In Fallujah, city negotiator Sheik Khaled al-Jumeili was released from U.S. custody, three days after he had been detained following the breakdown of peace talks with the Iraqi government.

Al-Jumeili, who spoke to the Associated Press from his home, said he had been detained by U.S. troops, along with three others, on Friday. Witnesses said the Islamic cleric had been picked up after he left a mosque following Friday prayers in a village about 10 miles south of Fallujah.

Al-Jumeili said the four men were taken to a Marine base outside Fallujah and then transported by helicopter to another location.

During his detention, Al-Jumeili said he was well treated by the Americans, and was not handcuffed or blindfolded like his companions. The other three men have not been released, he said.

Al-Jumeili said he was exhausted from his ordeal and made only one statement.

"I would like to tell all Iraqis that spies follow them everywhere and they must be vigilant," he said.

U.S. forces have been waging days of air and ground assaults in the insurgent bastion of Fallujah, targeting key planning centers of Jordanian-born terrorist Abu Musab al-Zarqawi and his group Tawhid and Jihad, which has claimed responsibility for numerous suicide bombings and hostage beheadings.

On Sunday, an Internet statement from Tawhid and Jihad claimed allegiance to Osama bin Laden and al-Qaida, saying it would follow bin Laden's orders from now on.

Allawi had demanded on Wednesday that Fallujah leaders turn over al-Zarqawi, who is believed to be in the area, or else face military action.

The latest attacks began Thursday after Fallujah clerics rejected the "impossible" demand to turn over the terrorist leader, insisting that al-Zarqawi was not in the city.

On Sunday, the crackle of automatic weapons fire and the thud of artillery echoed across Fallujah, 40 miles west of Baghdad, as fighting between American troops and insurgents raged on the eastern and southern edges of the city, witnesses said.

Clashes blocked the main road leading to Baghdad, and plumes of smoke rose above the flat-roofed houses in the city's Askari and Shuhada neighborhoods.

Witnesses said a Humvee was seen burning in the eastern edge of the city, and hospital officials reported three civilians were killed. The U.S. military reported no casualties.