A U.S. offensive aimed at Al Qaeda (search) in Iraq insurgents in western Iraq entered its third day Monday, with airstrikes in a town on the banks of the Euphrates River (search), witnesses said. At least 36 militants have died since the fighting began, officials said.

No serious U.S. casualties have been reported in the "Iron Fist" offensive by 1,000 Marines, soldiers and sailors near the Syrian border.

In Baghdad, Iraq's oil minister narrowly survived an assassination attempt when a roadside bomb blasted his seven-car convoy, killing three of his escorts, officials said.

Elsewhere, roadside bombs and fighting between insurgents and Iraqi forces on Monday wounded at least seven Iraqis in Ramadi, a militant stronghold 70 miles west of the capital, police and hospital officials said.

Insurgents wearing black hoods were seen carrying machine guns and rocket-propelled grenades in the city's streets, and Iraqi civilians gathered around two burning Iraqi army pickup trucks. Some of the civilians celebrated the destruction by carrying Iraqi military helmets and a uniform that appeared to have been pulled from the burning Iraqi vehicles.

In the northern city of Mosul, a drive-by shooting killed Nafi'a Aziz, a female member of Ninevah's provincial council, and her son, said police spokesman Brig. Saeed Ahmed. Aziz was in charge of the council's human rights committee and a member of the Patriotic Union of Kurdistan, the party of Iraqi President Jalal Talabani (search).

Mosul is 225 miles northwest of Baghdad.

The offensive and street fighting come less than two weeks before the national referendum on a new Iraqi constitution. Al Qaeda in Iraq and other groups in the Sunni-led insurgency have killed at least 207 people over the past eight days in a bid to wreck the vote.

On Sunday, Al Qaeda in Iraq claimed to have taken two U.S. Marines captive during the fighting and threatened to kill them within 24 hours unless all female Sunni detainees are released from U.S. and Iraqi prisons in the country. The U.S. military said the claim appeared false but that it was conducting checks "to verify that all Marines are accounted for."

On Monday, coalition forces announced the arrest late last week of 12 Iraqis suspected of being involved in an illegal local committee that punishes violators of Islamic law in Sadr City (search), a section of Baghdad partially controlled by radical Shiite cleric Moqtada al-Sadr.

Al-Sadr's militia, the al-Mahdi Army, was a stubborn problem for American forces until a truce was negotiated about a year ago.

The U.S. offensive in western Iraq by 1,000 Marines, soldiers and sailors began early Saturday in the village of Sadah and has since spread to Karabilah and Rumana, two nearby towns on the banks of the Euphrates River. On Monday, witnesses told The Associated Press that helicopter attacks on Rumana were sending up clouds of black smoke.

No casualties were immediately reported in Monday's fighting by the witnesses, who spoke on condition of anonymity out of concern for their own safety, or by the U.S. military command center in Baghdad.

The military says Al Qaeda in Iraq, the country's most feared insurgent group, has turned the area near Iraq's border into a "sanctuary" and a way-station for foreign fighters entering from Syria.

In Karabilah, Marines clashed with insurgents who opened fire from a building on Sunday in a firefight that killed eight militants, the military said.

Most of the militants appeared to have slipped out of Sadah before the force moved in, and hundreds of the village's residents fled into Syria ahead of the assault.

There was "virtually no opposition" in Sadah, the Marine commander in western Anbar province, Col. Stephen W. Davis, told The Associated Press.

At least 28 militants were killed in fighting Sunday, Davis said, bringing the two-day toll among insurgents to 36. There have been no serious U.S. casualties in the operation, he said.

On Monday, a journalist embedded with Marines in eastern Karabilah filed video showing the attack. About 20 Iraqi civilians fled the fighting, and the wounded included an Iraqi mother, father and their child, who were bleeding after being hit by flying pieces of concrete.

At one point, it was reported that as Marine snipers fired from rooftops and U.S. helicopters flew overhead, the military's advance into eastern Karabilah was slowed for about an hour by sporadic gunfire from suspected militants.

In Baghdad, Iraqi Oil Minister Ibrahim Bahr al-Uloum (search) survived an apparent assassination attempt on Monday when a roadside bomb blasted his seven-car convoy, killing three of his bodyguards, officials said.

The attack, which left Bahr al-Uloum with no injuries, occurred at 9:30 a.m. as he was traveling north for a ceremony to open a rebuilt oil refinery in the city of Beiji.

Iraq's oil industry has the world's third-largest known reserves, but it has been crippled by war, sanctions and the insurgency. Oil production remains limited, curbed by decaying infrastructure and frequent attacks on pipelines and refineries by militants.

Also Sunday, political differences among Iraqi leaders deepened ahead of the crucial Oct. 15 national vote on a new constitution.

Talabani, Iraq's Kurdish president, urged Shiite Prime Minister Ibrahim al-Jafaari to step down over accusations he is monopolizing power in the government and ignoring his Kurdish coalition partners' demands, a spokesman for Talabani's party said.

Elsewhere, Shiite militiamen released the recently kidnapped brother of Iraq's interior minister, the freed man, Abdul-Jabbar Jabr, told Associated Press Television News.