The New Nation - Internet Edition

AP, Washington

Three Americans including a US soldier were killed in Iraq violence.

The State Department is instructing all personnel at the U.S. Embassy in Baghdad not to leave reinforced structures due to incoming insurgent fire that has killed two American government workers this week.

Also Thursday, a U.S. soldier was killed by a roadside bombing in mostly Shiite eastern Baghdad, the U.S. command said. No further details were released.

One American, a government employee, died in Thursday's attacks on the Green Zone, four days after an American financial analyst was mortally wounded there.

A memo sent to embassy staff and obtained by The Associated Press says employees are required to wear helmets and other protective gear if they must venture outside and strongly advises them to sleep in blast resistant locations instead of trailers that most occupy.

The memo was sent after a second American citizen was killed by a rocket attack in the Green Zone on Thursday. A U.S. citizen military contractor died of his wounds on Monday after being severely injured with four others in an attack.

Meanwhle, Prime Minister Nuri al-Maliki vowed Thursday to pursue a crackdown on Shiite gunmen despite protests and mounting casualties, as Iraqi forces battled militias in Basra and Kut and slapped a three-day curfew on Baghdad.

Iraq's military authorities imposed a total curfew in Baghdad until Sunday to contain the fighting between Shiite militants and Iraqi troops, security officials told AFP, adding that the lockdown would be effective until dawn Sunday.

At least 105 people have died countrywide in clashes since Maliki ordered his troops to crack down on "lawless gangs" in Basra on Tuesday, according to official reports. Some sources have put the toll at double that.

Iraqi troops have clashed with Shiite gunmen in areas controlled by Sadr's so-called Mahdi Army since Tuesday, severely straining a "freeze" he ordered of the militia's activities last August.

Sadr appealed late Thursday for a "peaceful and political solution to end the crisis," according to a statement which a Sadr official in Najaf said would be distributed to the cleric's supporters across Iraq.

In Baghdad, Sadr's followers had earlier staged noisy protests against the crackdown in Basra and demanded the resignation of Maliki, who is personally overseeing the military operations.

The prime minister vowed not to back away from the military onslaught, despite Sadr's threat to launch a civil revolt if the attacks continued.

"We have come to Basra at the invitation of the civilians to do our national duty and protect them from the gangs who have terrified them and stolen the national wealth," he said in a statement.

Basra has become the theatre of a turf war between the Mahdi Army and two rival Shiite factions -- the powerful Supreme Iraqi Islamic Council (SIIC) of Abdel Aziz al-Hakim and the smaller Fadhila party.

In an interview with state television Al-Iraqiya, Maliki said the operation was not aimed at any particular political faction.

"Frankly we don't care who these gangs are linked to," he said.

"They violated laws, attacked property and killed innocents. We were surprised, however, that a specific political faction just exploded and gathered its forces to block the work of the government and started to attack the police," he added, without identifying the group.

Maliki's offensive drew praise from US President George W. Bush, who called the fighting in Basra a "positive moment" for the development of Iraqi security forces and proof the Baghdad government could defend itself.

Fighting in the city of Kut, 175 kilometres (110 miles) southeast of Baghdad, killed four police and 40 Shiite militiamen, police chief Abdul Hanin al-Amara told AFP.

"The security forces launched an operation at around midnight (2100 GMT Wednesday) to take back areas under the control of Shiite gunmen," Amara said, adding that police were now in control of the neighbourhoods.

An AFP correspondent in Basra, meanwhile, said heavy fighting erupted early Thursday in the central Jumhuriyah neighbourhood, a Mahdi Army bastion, where militiamen attacked troops with mortars, machineguns, rocket propelled grenades and small arms fire.

Police said Basra police chief Major General Abdul Jalil Khalaf survived a suicide car bomb attack in central Basra but three policemen were killed.

A pall of thick black smoke hung over the port city after a blast damaged an oil pipeline transporting crude from Zubair oil field to the Al-Faw storage facility.

Samir al-Maksusi, spokesman for the Southern Oil Company, said a fire caused by the blast had been extinguished, but that exports would be directly affected.

"The technical crew needs 48 to 72 hours to repair the pipeline," he said.