BAGHDAD, Iraq – Iraqi and American forces captured a suicide bomber before he could detonate his explosive belt yesterday, and announced a key suspect in the kidnap-slaying of Egypt’s top envoy to Iraq had been arrested in what was hailed as a blow to the terror network.

The thwarted suicide attack – just 150 feet from the Green Zone, the site of the U.S. Embassy and major Iraqi government offices – was intended to be part of coordinated assaults by a suicide car bomber and two pedestrians strapped with explosives.

The attackers apparently planned to detonate the car bomb first. Then the two pedestrians would blow themselves up in the midst of troops, police, and rescue workers rushing to the scene, American officials said.

The car bomb exploded successfully. But one pedestrian bomber was killed after an Iraqi policeman shot him, setting off his explosive vest, a statement from the Americans said.

The second pedestrian bomber was wounded by shrapnel from the blast before he could detonate his own vest, and was in critical condition at a U.S. military hospital in the Green Zone, the statement said.

Five policemen and four civilians also were wounded by the blasts and gunfire, officials at Yarmouk Hospital said.

Would-be bombers are rarely captured in Iraq. A 19-year-old Saudi was taken into custody after he somehow survived the explosion of his fuel tanker in December, a blast that killed nine people. A Yemeni was arrested in 2003 when his car bomb failed to detonate at a Baghdad police station.

There was no word on the identity of the failed bomber, but his arrest could yield valuable intelligence on the shadowy network of Islamic extremists – many of them believed to be foreigners linked to Al Qaeda.

In another setback to insurgents, about 30 suspected Al Qaeda members were arrested in the past week, including a key suspect in this month’s killing of an Egyptian envoy, Ihab al-Sherif, and attacks on senior diplomats from Bahrain and Saudi Arabia, the American command said.

Khamis Abdul-Fahdawi, known as Abu Seba, was captured Saturday after operations in the Ramadi area west of Baghdad, the military said. He is a suspect in the “attacks against diplomats of Bahrain, Pakistan and the recent murder of Egyptian envoy” al-Sherif, the U.S. statement said.

Another top suspect, Abdullah Ibrahim al-Shadad, or Abu Abdul-Aziz, was arrested during a raid Sunday in Baghdad, the statement said. It identified him as the operations officer for Al Qaeda in Iraq, led by Jordanian Abu Musab al-Zarqawi. Abu Abdul-Aziz was cooperating with coalition forces, according to the American command.

In an Internet statement yesterday, Al Qaeda in Iraq acknowledged that Abu Abdul Aziz had been apprehended but played down his importance.

Al Qaeda also denied any role in the Baghdad suicide car bombing Wednesday that killed 27 people, including 18 children and teenagers and an American soldier. The bomber detonated his SUV as American troops were distributing candy and toys in a mostly Shiite Muslim area known as New Baghdad.

“We, the al-Qaida organization in Iraq, announce that we are not in the least responsible for the New Baghdad operation that took place Wednesday,” said the statement posted and signed by Abu Maysara al-Iraqi, the Al Qaeda spokesman.

“Our sheik, Abu Musab al-Zarqawi … is very keen not to attack the rank and file and he himself is the one who directly supervises, plans and direct all the operations,” the statement said.

The statement – which could not be verified as authentic – suggests the militant group is aware of the backlash against the Sunni-led insurgency that the killings of so many children could generate – even among Iraqis who oppose the presence of American-led forces.

“Such action has nothing to do with religion,” Inaam Hassan, 38, said of the attack. “This tarnishes the image of the true resistance. I demand that the terrorists be executed in public to avenge the mothers who have lost their children.”

Salam al-Rubaiei, 33, said he regretted the deaths of so many children but blamed their parents for allowing them to approach American soldiers.