Sectarian violence has raged in the region and tit-for-tat kidnappings and revenge killings are common, but nothing had been reported on the scale of Wednesday's mass abduction. The al-Nasr plant is between Baghdad and Taji, a predominantly Sunni Arab area.

In the capital, where a security crackdown has been in place for nine days, insurgent and sectarian bloodletting was muted Thursday, with no major violent incidents reported by midday.

Elsewhere, the speaker of Russian parliament's upper house said Thursday that negotiations were being held to secure the release of four Russian Embassy staffers kidnapped June 3 in Baghdad, a news agency reported Thursday. A fifth Russian was killed when the men were captured.

The comments by Federation Council speaker Sergei Mironov came a day after an al-Qaida-linked insurgent group said that it had decided to kill the four after a deadline for meeting its demands had passed. As of midday Thursday, there was no indication whether the four had been killed.

Mironov said that "round-the-clock" talks were being conducted to secure their release, but he did not say by whom and where, according to the RIA Novosti news agency.

The military said the four Marines were killed Tuesday in insurgency-ridden Anbar province, three of them in a roadside bombing and a fourth in a separate operation. A U.S. soldier also died Wednesday south of the capital, the military said, giving no further details.

At least 2,512 members of the U.S. military have died since the beginning of the Iraq war in March 2003, according to an Associated Press count. The figure includes seven military civilians.

The killings in Mosul occurred primarily in groups of ones and twos, with several of the dead found dumped throughout the city. All the victims died in targeted shooting attacks, Mosul police Capt. Ahmed Khalil told The Associated Press.

Lawyer Khamis al-Obeidi, a Sunni Arab who represented Saddam and his half brother Barzan Ibrahim, was abducted from his home Wednesday morning. His bullet-riddled body was found on a street near Baghdad's Shiite slum of Sadr City. Police provided a photo of al-Obeidi's face, head and shoulders drenched in blood.

Saddam's chief attorney, Khalil al-Dulaimi, blamed the killing on the Interior Ministry, which Sunnis have alleged is infiltrated by Shiite death squads. He said Saddam and his co-defendants had gone on a hunger strike to protest the killing.

The strike could not be independently confirmed. It was not the first time the defense team said Saddam and his co-defendants were refusing food.

On Feb. 28, al-Obeidi said Saddam and several other defendants ended a 16-day hunger strike to protest the chief judge in their trial. In December 2004, the U.S. military acknowledged that eight of Saddam's 11 top lieutenants went on a weekend hunger strike to demand jail visits from the international Red Cross.

Bushra al-Khalil, a Lebanese member of the defense team, said al-Obeidi was taken from his house by men dressed in police uniforms and driving four-wheel-drive vehicles used by Iraqi security forces.

However, al-Obeidi's widow, Um Laith, was quoted in The New York Times as saying the attackers wore civilian clothes. She said 20 men burst into their house while the couple and their children were sleeping, and identified themselves as members of an Interior Ministry security brigade.

There was no comment from the ministry.

The Times also quoted Iraqi witnesses as saying al-Obeidi was transported in a convoy by people known to belong to the anti-American Shiite cleric Muqtada al-Sadr's militia, the Mahdi Army.

Al-Obeidi was the third member of Saddam's defense team to be killed since the trial began Oct. 19. His colleagues said the slaying was an attempt to intimidate the defense before it begins final arguments July 10, a process that will take about 10 days.

Chief prosecutor Jaafar al-Moussawi said the trial would continue.