NAJAF, Iraq - The United States intensified pressure on a radical cleric Thursday, seizing the governor's office from his fighters in Najaf and killing an estimated 40 insurgents in battles east of the holy city, a U.S. official said.
In Baghdad, a suicide attacker detonated a car bomb outside the so-called Green Zone that houses the U.S. headquarters, killing five Iraqi civilians and a U.S. soldier.
The soldiers took control of the building in Najaf without a fight, but heavy gunfire was heard after they moved in and smoke rose over the city. Motorists fled the area through deserted streets, honking their horns. Fighters loyal to cleric Muqtada al-Sadr had controlled the building since they launched their rebellion April 4.
Fighting east of Najaf killed an estimated 40 militiamen around Kufa, said Capt. Roger Maynulet, commander of a tank company with the Army's 2nd Armored Cavalry Regiment. U.S. officers said American forces were sent to the east of the city to draw militia fighters away from the governor's office.
Chief U.S. administrator L. Paul Bremer announced the appointment of a new governor for Najaf province as part of the campaign to crack down on al-Sadr's militiamen.
Also Thursday, a videotape of a blindfolded man described as an Iraqi-American being held hostage in Iraq was shown on an Arab TV station. On the tape, the man pleaded for help
The Baghdad car bomb injured 25 people, including two American soldiers. The bomb, hidden inside an orange-and-white taxi, exploded outside a 3-foot-high concrete blast wall protecting a U.S. checkpoint.
The U.S. soldier who died in the car bombing was the 21st U.S. serviceman killed in Iraq in May. The injured included two U.S. soldiers and three Iraqi policemen, the U.S. military said.
The suicide bomber also died in the attack, the military said.
A statement on a Web site known for militant Islamic messages and signed by a group linked to al-Qaida claimed responsibility. The message was signed by the "military wing" of the "Monotheism and Jihad Group," which is believed led by Abu-Musab al-Zarqawi.
Al-Zarqawi, a Jordanian, is wanted by the United States for allegedly organizing terrorists to fight U.S. troops in Iraq on behalf of al-Qaida. U.S. officials have offered a $10 million reward for al-Zarqawi's capture.
Hours after the car bomb, a roadside bomb exploded on Saadoun Street, a busy commercial avenue on the east side of the Tigris River near the Palestine and Sheraton hotels. Two Iraqis were injured.
Also Thursday, the U.S. command said that two U.S. soldiers were killed and two were wounded when a roadside bomb exploded in Baghdad. A statement said the explosion occurred just before midnight Wednesday.
The attacks came as U.S.-led forces increased pressure on al-Sadr. In the past two days, an estimated 76 militiamen loyal to him have been killed in gunbattles and raids, including Thursday's fighting.
"I think we are going to gain momentum from now on," said Lt. Michael Watson, a platoon leader with the 2nd Armored Cavalry Regiment in Najaf.
In Najaf, soldiers moved into the area of the governor's office from four directions and took control of the building without a fight. Afterward, gunfire could be heard and U.S. helicopters were seen flying low over parts of the city.
"What we're doing is conducting operations where we see fit so that as we develop a target through intelligence, we'll go out to that target and do a precision operation and then move back out, because we really are knowledgeable about the sensitivities of the holy city," Army Lt. Col. Pat White told CNN.
Al-Sadr's forces last month seized government buildings and police stations in southern cities, including Najaf and Kufa.
In Baghdad's Sadr city, an overwhelmingly Shiite Muslim enclave and al-Sadr stronghold, militiamen ambushed four U.S. patrols. Ten attackers were killed in retaliatory gunfire, a U.S. officer said, speaking on condition of anonymity. There were no reports of U.S. casualties.
Moderate Shiites tried to persuade al-Sadr to back away from his confrontation with the United States - a reflection of their growing concern.
In Baghdad, Bremer announced the appointment of Adnan al-Zurufi as governor of Najaf province. Bremer said the "the difficulty and suffering of the people" of the region "cannot continue."
Special U.N. envoy Lakhdar Brahimi arrived in the capital for discussions aimed at forming a transitional government to take power June 30.
Also Thursday, gunmen assassinated the head of the local Agriculture Department in the northern city of Kirkuk in a drive-by shooting that also killed his driver and wounded his wife, police said.
Najib Mohammed, a Kurd, was riding in his car when the gunmen opened fire from another vehicle, Gen. Sherko Shakir said. Insurgents frequently target officials working for the government, accusing them of collaborating with Americans.
The blindfolded man shown on the Dubai-based Al-Arabiya channel spoke in English and identified himself as Aban Elias of Denver.
"I am a civil engineer working here in Baghdad," he said, adding that he worked for the Pentagon.
Elias, shown in a 20-second segment, appealed to Islamic associations to work for his release.
"I was kidnapped and I call upon Muslim organizations to interfere to release me," Elias said.
With the tape came a statement from a previously unknown group calling itself "The Islamic Rage Brigade." The group said Elias was kidnapped on May 3. It made no demands.
A British Defense Ministry spokesman said no decision has been made on whether to send more of its troops to Iraq, describing as "speculative" news reports that more than 2,000 Royal Marines are poised to go.
Prime Minister Tony Blair's government has repeatedly refused to comment on recent reports it is preparing to help plug the gap left by the withdrawal of Spanish, Honduran and Dominican troops. In a subtle shift Wednesday, he said Britain was discussing with its coalition partners the possibility of sending more troops to different areas of Iraq.
Britain has 7,500 troops in southern Iraq.
In Poland, new Prime Minister Marek Belka came under pressure from his junior coalition partner to set a date for withdrawing the key U.S. ally's troops.
Belka said it was too soon to set a date for bringing home Poland's 2,400 troops or to conclude their mission commanding a multinational force in south-central Iraq.
"We don't want to bail out, which would destabilize our sector," he told Radio Zet. "And frankly speaking this wouldn't bring us honor anywhere in the world."