Three US soldiers and an Iraqi police chief died in the latest violence sweeping Iraq as unidentified men blasted an oil pipeline which erupted in flames in the north of the country, halting limited exports via Turkey. In Baghdad and Mosul, Christians mourned and prepared to bury their dead from devastating coordinated attacks on five churches on Sunday evening which killed at least 10 people and wounded around 50. South of Baghdad, an Iraqi woman was killed and nine other people wounded, including six militiamen, in clashes on Monday night between US troops and loyalists of Moqtada Sadr outside the radical cleric's Najaf home. The US military announced the deaths of the three US soldiers in two statements on Tuesday. "One marine assigned to 1st Marine Expeditionary force died of wounds received in action today in the Al-Anbar province while conducting security and stability operations," a statement said without elaborating. Another statement said two soldiers were killed and two wounded after they were hit by a roadside bomb in Baghdad at about 11:00 pm on Monday. Al-Anbar province includes the flashpoint Sunni Muslim cities of Fallujah and Ramadi. Marine posts in Fallujah, 50 kilometers (30 miles) west of Baghdad, are frequently attacked by resistance men with small arms, mortars and rocket-propelled grenades. In another bomb ambush in Baghdad, police chief Colonel Moyad Bashar al-Shamari was killed on Tuesday as he travelled to his office at the Mamoun police station. His car hit an improvised bomb near the Abu Jafaar al-Mansour Square. In another blow to the country's efforts to get back on its feet, oil exports through Iraq's pipeline connecting the northern fields of Kirkuk with the Turkish port of Ceyhan came to halt Tuesday after a major attack, according to a Northern Oil Company official. Also in Najaf, stronghold of Moqtada Sadr, a spokesman for the cleric lashed out at the US military on Tuesday. He accused US troops of seeking to arrest the wanted cleric and to plunge Iraq's Shiite cities back into chaos following a bloody standoff between Sadr's militia and US-led troops earlier this year that left hundreds dead. The US military denied that it surrounded Sadr's home, saying marines who were on a patrol in the area were fired at by militiamen with small arms fire and rocket-propelled grenades, prompting them to fire back. The confrontation followed the arrest by multinational forces on Saturday of Sheikh Mithal al-Hasnawi, Sadr's representative in Karbala, and is the most serious incident between US troops and Sadr's militiamen since a truce in early June that ended the fighting. **PHOTO CAPTION*** Iraqi policemen transport the coffin of their slain chief from Baghdad's Yarmuk Hospital to his family house in Baghdad. (AFP)