Baghdad, Iraq ? A suicide bombing killed the head of the U.S.-appointed Iraqi Governing Council on Monday as his car waited at a checkpoint near coalition headquarters, a major setback to American efforts to stabilize Iraq just six weeks before the handover of sovereignty.

A roadside bomb containing deadly sarin nerve agent also exploded “a couple of days ago” near a U.S. military convoy in Baghdad, Brig. Gen. Mark Kimmitt said Monday, adding two explosives experts were treated for “minor exposure.”

However, Defense Secretary Donald Rumsfeld said the results were from a field test, which can be imperfect, and said more analysis was needed. If confirmed, it would be the first finding of a banned weapon upon which the United States based its case for war.

Two American soldiers were killed in action Monday in Anbar province west of Baghdad, the military said. The troops were assigned to the 1st Marine Expeditionary Force, but the military declined to release other details, citing security concerns.

Izzadine Saleem, also known as Abdel-Zahraa Othman, was waiting in a Governing Council convoy at a U.S. checkpoint along a tree-lined street preparing to enter the Green Zone when the bomb was detonated. It apparently had been rigged with artillery shells and hidden inside a red Volkswagen.

Iraqi officials said nine people, including the bomber, were killed and 14 Iraqis and an Egyptian were wounded in Monday’s attack. Kimmitt put the death toll at seven. Two U.S. soldiers were slightly wounded.

Transfer still on

Iraqi and coalition officials vowed that the power transfer would take place on June 30, as scheduled, despite the attack.

Secretary of State Colin Powell called Saleem an Iraqi patriot. “Terrorists may have taken his life, but they will never be able to kill his dreams or those of the Iraqi people.”

A U.S. Army soldier secures the site where the head of the Iraqi Governing Council was killed in a car bombing near a U.S. checkpoint in central Baghdad, Iraq. Izzadine Saleem was among nine Iraqis killed Monday in the blast.

Saleem, a Shiite Muslim in his 60s, held the rotating presidency of the 25-member Governing Council for May. He was the second council member slain since appointment last July; Aquila al-Hashimi was mortally wounded by gunmen in September on her way to work.

Insurgents also have targeted police and army recruitment centers and other Iraqis perceived as owing their positions to the Americans.

The U.S. military said the car bombing was a suicide attack and Kimmitt said it had the “classic hallmarks” of Abu Musab al-Zarqawi, a Jordanian-born militant with links to al-Qaida.

However, a previously unknown group, the Arab Resistance Movement, claimed responsibility, saying in a Web site posting that two of its fighters carried out the attack on “the traitor and mercenary” Saleem.

Kimmitt said he did not know if the Arab Resistance Movement was “a cover for the Zarqawi network or if it’s an actual organization.”

Al-Zarqawi is believed responsible for many of the vehicle bombs in Iraq in recent months and for the beheading last week of U.S. civilian Nicholas Berg.

The Governing Council selected Ghazi Mashal Ajil al-Yawer, a Sunni Muslim civil engineer from Mosul, to succeed Saleem. Al-Yawer will lead the council until June 30, when sovereignty will be transferred to a new interim Iraqi government.

Appearing before reporters with several council colleagues, al-Yawer promised the Iraqi leadership would continue “the march toward building a democratic, federal, plural and unified Iraq.”

“God willing, the criminal forces will be defeated despite all the pain they are causing to our people and their heroic leaders,” he said.

Sarin bomb likely scavenged

According to Kimmitt, the sarin explosion was confirmed by the Iraqi Survey Group, a U.S. organization that has searched for weapons of mass destruction since Saddam’s ouster last year.

The sarin was in an artillery shell that had been rigged as a bomb, Kimmit said. It was discovered by a U.S. convoy and exploded before it could be defused; the explosion released a small amount of sarin, Kimmitt said.

He said he believed that insurgents who rigged the artillery shell as a bomb didn’t know it contained the nerve agent. “The former regime had declared all such rounds destroyed before the 1991 Gulf War,” Kimmitt said.

Two former U.N. weapons inspectors, Hans Blix and David Kay, said the shell was likely scavenged from a dump and did not signify Iraq had stockpiles of such weapons.

Sarin is a deadly substance that blocks the transmission of key nervous system enzymes, causing convulsions, paralysis, loss of consciousness and potentially fatal respiratory failure. Low-level exposures can be treated with antidotes, if administered quickly.