U.S. warplanes pounded targets in a large Shiite Muslim slum in the eastern part of the capital early Thursday morning, part of an operation aimed at dismantling the militia loyal to the rebel cleric Moqtada Sadr.

The attacks killed at least one person and injured 12, according to hospital officials.

Although Shiite insurgents in the holy city of Najaf have been largely quiet since a truce between Sadr's militia and U.S. and Iraqi forces there was reached a month ago, clashes have continued in the Baghdad slum of Sadr City. U.S. authorities say they are eager to resume reconstruction projects in the neighborhood but have been hampered by the continued violence.

"The main problem is that he has the militia," Maj. Bill Williams, an acting battalion commander in the Army's 1st Cavalry Division, told the Associated Press. "Our goal is to pressure him to disband and disarm."

Meanwhile, there was no word regarding the fate of a British hostage whose captors threatened to kill him if U.S. authorities did not release Iraqi female prisoners in their custody.

The hostage, Kenneth Bigley, who was working for a foreign construction company, was abducted last week with two American colleagues. Both of those men, Eugene "Jack" Armstrong and Jack Hensley, were beheaded by a militant Islamic group headed by Abu Musab Zarqawi, a Jordanian-born militant.

On Wednesday, the group, Monotheism and Jihad, released a video in which Bigley pleaded with Tony Blair, the British prime minister, to intervene and save his life. But Blair's government has said it will not negotiate with terrorists, a posture in accord with that of the United States.

A group calling itself the Brigades of the Victorious Lion of God said Thursday that it had released a Canadian hostage who worked for a company that provided equipment for several U.S. bases.

The Canadian government on Thursday confirmed the release of Fairuz Yamulky, the chief operating officer for GSF Cement and Sand Co.

Relatives of Yamulky, an Iraqi Kurd whose family fled Iraq for Canada in 1991, told the Calgary Sun that the 38-year-old had been snatched from her vehicle by gunmen on a Baghdad street on Sept. 5, the Associated Press reported.

The status of two Italian aid workers abducted Sept. 7 from a Baghdad office remained unknown Thursday, a day after a group claiming to hold them said the two had been killed. The Italian Foreign Ministry issued a statement saying it had no new information on the pair, Simona Torretta and Simona Pari.

A little-known group called Supporters of Zawahiri -- a reference to Ayman Zawahiri, the No. 2 figure in al Qaeda -- was the first to assert responsibility for the women's kidnapping. But a second group, the Islamic Jihad organization in Iraq, also has claimed to be holding them.

In the city of Fallujah, sources close to the Mujaheddin Shura Council -- 18 clerics, tribal sheiks and former Baath Party members who run the city and elements of the insurgency -- said council leaders were angered by the women's abduction and called on their captors to release them on the grounds that it is "unethical" for Arabs and Muslims to kidnap women. The kidnappers refused, the sources said.

Despite the transfer of political power to an interim Iraqi government in June, the U.S. military has continued to take responsibility for security in Iraq, struggling through months of insurgent attacks, car bombings, assassinations of government officials and kidnappings of both foreign and Iraqi workers.

A U.S. Marine was killed Wednesday while conducting security operations in the western province of Anbar, the military said Thursday. The Marine was assigned to the 1st Marine Expeditionary Force. No further details were disclosed, and the victim's name was being withheld.