Coalition spokesman Dan Senor said 40 foreign civilians are being held hostage in Iraq. "The FBI is working with coalition forces and with Iraqi security forces to seek out the hostage takers and the hostages," he said. "We will not negotiate with terrorists and kidnappers."

And he warned Iraqis and civilians in Iraq from coalition countries that terrorism may increase before and after the scheduled June 30 handover of power. "We recognize there will still be a major terror threat here after the Iraqi people have sovereignty," he added.

Meanwhile, about 2,500 coalition troops are poised to move into the Shiite holy city of Najaf where General Mark Kimmitt says anti-coalition militias led by rebel cleric Moqtada al-Sadr pose a significant threat. "The force that is being brought in that region is powerful, it will be disciplined and it will be capable of conducting the full spectrum（范围）of military operations," he said.

Those operations were put on hold while a Shiite pilgrimage to the city was underway. U.S. troops briefly detained a representative of the Shiite cleric at a Baghdad hotel Tuesday, but released him after judging him not to be a threat.

While coalition forces are trying to find him, Moqtada al-Sadr gave an interview to Lebanese television in which he urged his followers to continue fighting against the occupation even if he has to sacrifice（牺牲）his life for his country.

Meanwhile in western Iraq, resistance has been coming from Sunni fighters and more fighting broke out in the town of Fallujah with U.S. Marines using heavy weapons against insurgents. However, General Kimmitt said Marines have been generally observing a ceasefire. He added, "Many of these attacks that are being conducted by the enemy in Fallujah are meant to be provocative（煽动的）."

At least two more American troops have been killed in Iraq during the past two days.