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A roadside bomb killed seven U.S. soldiers in northwest Baghdad (search) and two Marines were killed in western Iraq on Thursday, the deadliest day for American forces since an attack on a U.S. base last month.

The bombing came as Iraq extended a state of emergency by 30 days to battle militants whose attacks have surged ahead of this month's elections. The prime minister warned the number of assaults would only rise as voting day draws closer.

Just three weeks before the Jan. 30 elections, the commander of U.S. ground forces in Iraq acknowledged that security is poor in four of 18 Iraqi provinces. But Lt. Gen. Thomas Metz (search) told a briefing in the capital that delaying the vote would only increase the danger.

"I can't guarantee that every person in Iraq that wants to vote, goes to a polling booth and can do that safely," Metz said. "We're going to do everything possible to create that condition for them, but we are fighting an enemy who cares less who he kills, when he kills and how he kills. A delay in the elections just gives the thugs and terrorists more time to continue their intimidation, their cruelty, their brutal murders of innocent people."

The soldiers with Task Force Baghdad (search) were on patrol Thursday evening when their Bradley fighting vehicle hit the explosive, the military said in a statement. Everyone inside the Bradley was killed.

No other details were immediately available about the latest attack. But Iraq's insurgents have frequently targeted American troops with crude explosives planted in roads and detonated remotely as patrols pass.

The two other U.S. Marines killed in action Thursday were both members of the 1st Marine Expeditionary Force and lost their lives in Anbar province, which is home to the volatile city of Fallujah.

The previous four days had seen a string of assassinations, car bombings and other assaults that killed 90 people.

On Tuesday, five American troops were killed, including three Task Force Baghdad soldiers who died in a roadside bombing, one who was slain in Anbar, and another who died in Balad, north of Baghdad.

But Thursday's toll was the highest for the U.S. military in Iraq since a bombing at a mess tent in Mosul on Dec. 21 killed 22 people, including 14 U.S. soldiers and three American contractors.

The latest deaths brought the number of U.S. troops killed since the beginning of the Iraq war in March 2003 to 1,350, according to an Associated Press count. At least 1,063 died as a result of hostile action.

The military said the names of the troops who died Thursday were being withheld until their families are notified.

As militants continued with the attacks, Iraqi authorities made some grisly discoveries. Police in the southern city of Basra found two charred and beheaded bodies in a house used by election officials. Police also announced they found the bodies of 18 young Shiites killed last month while seeking work at a U.S. base.

The state of emergency, originally announced two months ago, was extended for 30 days throughout the country except for the northern Kurdish-run areas, a government statement said. The decree includes a nighttime curfew and gives the government additional power to make arrests and launch military or police operations.

Interim Prime Minister Ayad Allawi said he expected the number of attacks would rise before the Jan. 30 vote and called the decision on prolonging the state of emergency a precaution. He blamed former members of Saddam Hussein's regime for the continuing violence.

"Saddam's followers, who have intensely shed the blood of our people and army, are still in action clandestinely, allying with a bunch of criminals, murderers and terrorists who are the enemies of our people and our progress," Allawi said during a ceremony to mark the national Army Day holiday.

"Our army and police have become targets of these hateful forces that fear the formation of the people's army and police."

Allawi, a secular Shiite, is insisting the elections go forward, despite calls from some Sunni religious leaders for a boycott. Sunni Arab political parties have largely withdrawn from the race because of security fears, particularly in western Iraq. Some have sought a delay of the vote.

The United States strongly opposes a postponement. Metz acknowledged U.S. forces "continue to deal with violence and lawlessness in some areas," specifically citing Nineveh, Anbar, Salahadin and Baghdad provinces. But he said other areas were secure enough to allow the elections to go ahead.

Foreign ministers of neighboring countries issued a statement Thursday saying they "stood strongly behind the interim government of Iraq" and "urged all segments" of society to participate in the elections.

The election is expected to shift power to the Shiite Muslim community, an estimated 60 percent of the population that had been dominated by the Sunni Arab minority since modern Iraq was created after World War I.

The call was backed by Jordan, a Sunni-dominated neighbor that had previously supported postponing the election. King Abdullah II had also suggested the elections would produce an Iraq controlled by Shiites who would quickly align themselves with Iran, ruled by a Shiite theocracy.

But Jordanian Foreign Minister Hani al-Mulqi insisted the elections be held as scheduled.

"From this podium, I call on all factions of the Iraqi people, young and old, men and women, to go to the polls to choose their representatives and draw their own future," al-Mulqi said. Failing to do that "will leave the door open for others to choose for them."

The charred bodies of the two beheaded Iraqi policemen were found in a house in Basra used by officials organizing the election, police said.

In the deaths of the 18 Iraqis seeking work with the Americans, police said the insurgents shot the young men — ranging in age from 14 to 20 — on Dec. 8 after stopping two minibuses about 30 miles west of the volatile city of Mosul, 225 miles north of Baghdad.

Their hands were tied behind their backs and each was shot in the head, police said. All were Shiites from Baghdad who had been hired by an Iraqi contractor to work at a U.S. base in Mosul.

The bodies were discovered Wednesday, the day an attacker blew up an explosives-laden car outside a police academy south of Baghdad, killing 20 people. A second car bomber killed five Iraqi policemen in Baqouba. Both attacks were claimed by Al Qaeda in Iraq, the group led by Jordanian terrorist Abu Musab al-Zarqawi.

Iraqi forces announced the arrest of Abdul Aziz Sa-dun Ahmed Hamduni, a leader of al-Zarqawi's group in Mosul.