Insurgents in western Iraq set off three chlorine gas car bombs, US forces said on Saturday, weeks after two similar attacks sparked fears of a new campaign using unconventional weapons in Iraq.

The Friday attacks, which the US military said made hundreds ill and killed at least two, came a month into a US- Iraqi security crackdown in Baghdad aimed at stemming sectarian violence that threatens to pitch Iraq into outright civil war.

The US military said two suicide bombers driving dump trucks carrying chlorine made 350 people ill near the town of Falluja on Friday, and a smaller car bomb near Ramadi also released chlorine, though there were few casualties.

The US statement reported two deaths in one of the attacks but hospital sources said earlier eight people were killed and dozens became ill after the two bombings in the Falluja area.

The US military announced the combat deaths of six soldiers, four killed by a roadside bomb in western Baghdad and one shot dead in Baquba, north of the capital on Saturday. Another died in a bomb blast south of Baghdad on Friday.

Chlorine gas was widely used in World War I but its use in insurgent attacks in Iraq has particular resonance there. Saddam Hussein attacked Kurdish areas with chemical weapons in the 1980s during the Iran-Iraq war.

Two bombs with chlorine killed eight people earlier this year. It causes severe burns when inhaled and can cause death.

The US military said they discovered an Al-Qaida car bomb factory last month near Falluja with chlorine tanks.

Anbar, a mainly Sunni Arab province in which Falluja lies, has long been among the most troublesome areas of Iraq for US forces.

Friday's two bombs near Falluja exploded within 40 minutes of each other.

In the first, near the town of Amiriya, two Iraqi police were killed and up to 100 Iraqis showed signs of chlorine exposure, with symptoms ranging from minor skin and lung irritation to vomiting, the US statement said.

Soon afterwards, a suicide bomber detonated a dump truck carrying a 900-liter chlorine tank rigged with explosives south of Falluja. Around 250 civilians became ill.

Earlier on Friday, a smaller bomb using chlorine detonated at a checkpoint northeast of Ramadi, the capital of Anbar, wounding one US soldier and one Iraqi civilian.

Hospital sources said one of the Falluja attacks targeted a large housing complex, killing six people including policemen, while the second targeted a tribal leader opposed to Al-Qaida.

(China Daily via agencies March 19, 2007)