Coffins carrying the bodies of more than 200 Iraqis killed by car bomb and mortar attacks set off today on a grim 100-mile funeral procession from the Shia Muslim slums of Baghdad to a holy city in the south.

Crying, chanting and beating their chests as they mourned the loss of their loved ones, around 300 men, women and children walked alongside vehicles carrying the caskets of the dead, killed in what was the deadliest attack in Iraq since the US-led invasion in 2003.

As the grief-stricken procession reached the edge of Sadr City, the Shia enclave that was the scene of yesterday’s destruction, the cars and vans left most of the mourners behind, beginning the long journey south to Najaf, the holy city that is the traditional burial place for Shias from across the world.

The drive is a notoriously treacherous one, passing through several checkpoints and areas controlled by Sunni militants in Iraq’s so-called "Triangle of Death."

Amidst cries of "God is great. There is no God but Allah," members of the crowd repeatedly touched the sides of the cars and vans holding the dead, as if to say a final goodbye to the scores of relatives and friends killed.

With Baghdad remaining under a 24-hour curfew aimed at halting further sectarian violence, the mourners were the only ones allowed on the streets of the capital together with police officers brought in to guard the processions upon the orders of Nouri al-Maliki, the Prime Minister who is himself a Shia.

The assault, believed to have been carried out by insurgents most likely from al-Qaeda, saw militants exploding five car bombs in brief intervals just after 3pm yesterday, shattering the Jamila market, al-Hay market and al-Shahidein Square in Sadr City. At around the same town mortar rounds struck the neighbourhood.

As the death toll rose to 215 with a further 257 wounded, radical Shias slammed coalition forces, accusing US troops of failing to provide security.

"We say occupation forces are fully responsible for these acts, and we call for the withdrawal of occupation forces or setting a timetable for their withdrawal," said Qusai Abdul-Wahab, a follower of the Shia cleric Hojatoleslam Moqtada al-Sadr.

His comments came as it emerged that al-Sadr, a key player in the Iraqi Government, had threatened to withdraw his allies from the Cabinet and parliament if Mr al-Maliki went ahead with his scheduled meeting with President Bush in Jordan next week.

The cleric's followers hold six Cabinet seats and have 30 members in the 275-member parliament.

"We asked Maliki to cancel his planned meeting with Bush because there is no reason to meet with the criminal who is behind terrorism in Iraq," Faleh Hasan Shanshal, a senior official in Sadr’s movement, told Reuters. "We will suspend our membership of the cabinet and parliament if he goes ahead."

Shia fighters quickly retaliated to yesterday’s onslaught, firing 10 mortar rounds in the Sunni neighbourhood of Adhamiyah, killing one person and wounding seven others.

Eight more rounds targeted the area near the offices of the Association of Muslim Scholars, the main Sunni organisation in Iraq, setting nearby houses on fire. This was followed later yesterday by two further mortar barrages on Sunni neighborhoods in west Baghdad, which killed nine and wounded 21.

The violence continued unabatted today. Two bombs exploded in northern Iraq, killing at least 22 people and wounding 26.

The attack in Tal Afar, 260 miles (420 km) northwest of Baghdad, saw a pedestrian wearing a suicide belt blow himself up at the same time as explosives hidden in a parked car went off outside a car dealership.

The bloodshed came as both British and US officials appeared to signal that coalition forces were considering moves to accelerate the hand-over of security responsibilities to Iraqi authorities.

"We condemn such acts of senseless violence that are clearly aimed at undermining the Iraqi people’s hopes for a peaceful and stable Iraq," Jeanie Mamo, White House spokesman, said in Washington.

Leaders from Iraq’s Shia, Sunni and Kurdish communities issued a televised appeal for calm, while Grand Ayatollah Ali al-Sistani, the most prominent Shia cleric in Iraq, condemned the bombings and urged self-control among his followers.

Iraq is suffering through a period of unparalleled violence, with the UN claiming yesterday that 3,709 Iraqi civilians were killed in October alone, the most in any month since the start of the war 44 months ago. It added that citizens were fleeing the country at a rate of 100,000 each month, and that at least 1.6 million Iraqis have left since March 2003.

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