FALLUJAH, Iraq (AFP) - US ground troops moved on the Iraqi rebel bastion of Fallujah after a night of deadly air assaults, and a car bombing in Baghdad killed one civilian in a bloody start to the Muslim holy month of Ramadan.
The nation's capital was reeling after Iraq's most wanted man Abu Mussab al-Zarqawi claimed two bomb blasts in Baghdad's once impenetrable Green Zone, home to the US embassy and Iraqi government, that left at least five people dead.
Before dawn, 1,000 US group troops, along with tanks and Iraqi special forces, rumbled toward Fallujah in a bid to flush out the Jordanian fighter Zarqawi, said to be the top Al-Qaeda operative in Iraq.
"Units are pushing forward... Their mission is to disrupt the enemy's ability to conduct terror attacks in this area of operations, specifically in the city of Fallujah... They'll do whatever it takes to accomplish that," said marines spokesman Lyle Gilbert.
The deployment was the biggest around Fallujah, the epicentre of the insurgency, since last April when marines and rebels battled to a draw in the community of 200,000 people, leaving it in the hands of radical Islamists for months.
The ground offensive followed a day of blistering air and artillery strikes on suspected Zarqawi hideouts that left eight Iraqis killed and 23 wounded, according to hospital sources.
Gilbert declined to say if the troops had yet entered the rebel bastion, but a storming of the city loomed after Iraqi Prime Minister Iyad Allawi said Wednesday Fallujah should surrender Zarqawi or face a military assault.
The air strikes and Allawi's fighting words contributed to a breakdown in the talks with Fallujah leaders to find a peaceful solution to the crisis, Fallujah officials said after a delegation from the troubled city walked away in anger from the negotiating table Thursday.
"Allawi and his government will bear the responsibility of the spilling of Muslim blood in Fallujah," one said.
As tensions soared, one Iraqi civilian was killed and at least 10 others wounded in a suicide car bombing targeting a police station in a southern Baghdad suburb, police and medical sources said.
A speeding car exploded near the police headquarters in Dura at 9:45 am (0645 GMT), a police officer told AFP. More wounded were being taken to hospital.
The attack sent chills up the spine of Baghdadis who worried for their safety during their sacred holiday after Zarqawi's Unity and Holy War group claimed the deadliest attack ever Thursday in the once impenetratable Green Zone.
A pair of bombers struck in a bustling restaurant and bazaar in the citadel-like area, killing at least five people, including three American private security contractors, while another US citizen was presumed dead in the back-to-back blasts Thursday, the State Department said.
The four dead were later identified as employees of Dyncorp, a US firm contracted to train Iraqi police.
There was no easy answer as to how the men, at least one of them a suicide bomber, and the other who probably planted a bomb, infiltrated the Green Zone, an embassy official said.
But some witnesses said they spotted the culprits just before the attacks. There were also fears that insurgents had recruited followers among the thousands of Iraqis whose homes fall inside the closed off US-Iraqi government enclave.
The US military said it feared more attacks over the Ramadan period inside their heavily-protected enclave.
"We have intelligence to be prepared for and to expect an increase in activity for attacks on the International Zone," said Lieutenant Colonel Steve Boylan.
The daring attack followed stepped-up security measures after the discovery of a bomb last week at the Green Zone cafe.
Meanwhile, dozens of militiamen and arms dealers lined up to hand over their weapons for cash at three police stations in Sadr City on the last day of an initiative for rebel cleric Moqtada Sadr's army to disarm in Baghdad.
And as the country moves forward to planned national elections in January, Iraqi President Ghazi al-Yawar said in an interview published in Cairo that the poll could be delayed if the security situation had not sufficiently improved.
In Warsaw, Poland's Prime Minister Marek Belka confirmed that the 2,500 Polish troops in Iraq would be progressively withdrawn starting from January next year and would not stay "an hour longer than needed."