A bodyguard detained at the home of a leading Sunni Arab politician is suspected of being a member of Al Qaeda in Iraq, thought to be involved in planning a major suicide car bombing assault inside Baghdad's fortified Green Zone, the U.S. command said Saturday.

Guard Khudhir Farhan was taken into custody Friday at the home of Adnan al-Dulaimi, the head of the largest Sunni bloc in parliament, al-Dulaimi told The Associated Press.

"The detained individual is suspected of involvement in the planning of a multi-vehicle suicide operation inside Baghdad's International Zone," the U.S. military said in a statement without identifying the suspect.

The zone in downtown Baghdad is home to the Iraqi government, parliament and the U.S. and other western embassies.

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"Credible intelligence indicates the individual, a member of Dr. Dulaimi's personal security detachment, and seven members of the detained individual's cell were in the final stages of launching a series of (car bomb) attacks inside the International Zone, possibly involving suicide vests," the military said.

The man is suspected of having links to a car bomb network operating in the southern area of Baghdad, the military said.

"He is believed to be a member of the Al Qaeda in Iraq group," the military said.

Immediately after the arrest Friday afternoon, al-Dulaimi denied the guard had any terrorist links, but when contacted Saturday he seemed to be retreating slightly from his previous comments.

"That individual joined my residence as a guard no more than a month ago, therefore I haven't got complete data about his background," al-Dulaimi said. "Anyhow, they are only suspicions about his involvement, which have not been proved."

The military later issued another statement saying al-Dulaimi cooperated with the soldiers when they showed up to apprehend the guard.

"This operation in no way implies Dr. al-Dulaimi was associated with any illegal activity; he was not the target in this operation," the U.S. command said.

Following the arrest, the Iraqi government ordered a complete lockdown of Baghdad to pedestrian and vehicular traffic through Sunday morning. The curfew was put into place on the advice of U.S. forces, Interior Ministry spokesman Brig. Abdul-Kaim Khalaf told the AP.

"They have information terrorists entered Baghdad," Khalaf said. "The prime minister agreed to (the curfew) to give our security forces the freedom of movement to raid certain places."