BAGHDAD, Feb 3: A suicide bomber killed 135 people on Saturday in the deadliest single bombing in Iraq since the US invasion in 2003, driving a truck laden with one ton of explosives into a market in a mainly Shia area of Baghdad.

The blast, which Prime Minister Nuri al-Maliki blamed on Saddam Hussein supporters and other Sunni militants, shattered fruit and vegetable stalls, caved in shop-fronts and left the smashed bodies of shoppers strewn in the street.

It came as US and Iraqi troops prepared for a planned offensive seen as a last-ditch effort to stem worsening sectarian bloodshed that kills hundreds in Baghdad every week.

“It was a terrible scene. Many shops and houses were destroyed,” said one resident, Jassem, 42, who rushed from his home to help pull people from the rubble after hearing the explosion that rocked central Baghdad.

“All Iraqis were shaken today by this crime,” Mr Maliki said in a statement in which he again spoke of his government's determination to crush the militants.

Police said 305 people were wounded. The casualties swamped the capital's hospitals. There were chaotic scenes at Ibn al-Nafis hospital in central Baghdad, where hallways overflowed with wounded on trolleys.

“I was in my shop and there was a great explosion and the roof fell in on me. I woke up here in hospital,” said one man at the hospital with blood streaming down his face.

Emergency workers dragged bodies from the debris and piled them on pickup trucks, a Reuters reporter at the scene said.

Saturday's blast came hours after Iraq's leading Shia cleric, Grand Ayatollah Ali al-Sistani, renewed an appeal to Iraqis to avoid violence.

“Everybody knows the necessity for us to stand together and reject the sectarian tension to avoid stirring sectarian differences,” his new fatwa, or religious edict, said.

In the worst previous single bombing in Iraq, a suicide car bomber killed 125 people in Hilla south of Baghdad in February 2005. In November 2006 six car bombs in different parts of the Sadr City neighbourhood of Baghdad killed 202 and wounded 250.

The latest bombing will again throw the spotlight on Mr Maliki's planned security sweep in the capital and whether it will succeed where other similar crackdowns have failed.

His critics say an offensive last summer failed because the Iraqi army committed too few troops and because he was reluctant to confront the Mehdi Army militia of cleric Moqtada al-Sadr, a key political ally.

An Iraqi militant group linked to Al Qaeda vowed in a Web recording on Saturday to widen its attacks to all parts of Iraq instead of just focusing on Baghdad and would only stop when “Bush signs a surrender accord”.

In the northern, ethnically mixed city of Kirkuk, seven car bombs, including a suicide attack, killed at least four people and wounded 37. Two of the cars detonated outside the offices of the main Kurdish parties in the city.

Further north, another curfew was imposed in Mosul, Iraq's third largest city, after clashes between insurgents and police erupted in several neighbourhoods.-—Reuters