A suicide truck bomb killed at least ten people on a major bridge in Baghdad this morning, wrecking the structure and sending several cars plunging into the river Tigris below.

The attack was the first of two spectacular bombings in the Iraqi capital today. Shortly afterwards a suicide bomber managed to slip through the elaborate security of the Green Zone to blow himself up in the canteen of the Iraqi parliament, killing at least two MPs and injuring 10 more.

The al-Sarafiya bridge was severely damaged in two places by this morning's pre-rush hour explosion, which collapsed the steel girders of one of the main crossing points in the northern half of Baghdad.

Iraqi authorities said that at least 26 people had been injured in the explosion but there were fears that the death toll could rise as police and dive teams searched the muddy waters of the Tigris for fallen vehicles and as many as 20 people who are thought to have been thrown off the bridge.

Witnesses reported that the bomb-laden lorry had parked in the middle of the structure before blowing up but there was speculation that explosives had also been set elsewhere on the bridge because it appeared to have been broken in two places.

"A huge explosion shook our house and I thought it would demolish our house. Me and my wife jumped immediately from our bed, grabbed our three kids and took them outside," said Farhan al-Sudani, a 34-year-old Shia businessman who lives near the bridge.

Reports said sections of the bridge had been reduced to crumbled concrete pilings and twisted metal. "We were astonished more when we saw the extent of damage," said Ahmed Abdul-Karim, a local resident. "I was standing in my garden and I saw the smoke and flying debris."

"It is one of Baghdad’s monuments. This is really damaging for Iraq. We are losing a lot of our history every day," he said.

The al-Sarafiya bridge is one of nine crossing points over the Tigris in Baghdad, but had gained a reputation as one of the safest ways to move around the north of the city because it connects Waziriyah and Utafiyah, two relatively stable neighbourhoods. Two of Baghdad's other bridges have already been closed for security reasons.

Designed by British engineers and built in 1949 by Holloway Bros, a London-based construction firm, the al-Sarafiya bridge was Baghdad's railway crossing over the Tigris and helped connect Basra to northern Iraq. It ceased to carry trains in the 1970s to make more room for cars but remains one of the most recognisable structures in the Iraqi capital.

"This bridge is linked to Baghdad’s modern history. It is one of our famous monuments," Haider Ghazala, an Iraqi architect told the AP. "Attacking this bridge effects the morale of Iraqis and especially Baghdad residents who feel proud of this bridge."

"They want to demolish everything that connects the people with this land," he said.

Residents of Baghdad said that the closure of the bridge would further complicate their attempts to move around the city, which is littered with army, police and militia roadblocks and currently the subject of a massive combined US and Iraqi attempt to control the endemic violence.

The Tigris, which winds through Baghdad, has become a de facto barrier between the mostly Shia east and Sunni west of the city, a division that has become sharper after months of sectarian warfare and the fleeing of thousands of people from formerly mixed neighbourhoods. There have been rumours for months of a bombing campaign to bring down the bridges.

Today's attack comes the day after the worst outbreak of fighting since the launch of "Operation Law and Order", considered the last-ditch American campaign to bring order to Baghdad.

Corpses lay unclaimed on the streets yesterday after a prolonged gunbattle between Iraqi and US forces and insurgents in the centre of the city. Two Iraqi soldiers and 18 "terrorists" were killed. A further 20 were captured. The US military said today that two more insurgents had been killed and 17 captured across Iraq.

Operation Law and Order is credited with reducing the death toll in Baghdad since it began in mid-February, but there has been a concurrent increase in violence and sectarian killings outside the capital as insurgents and militia groups are reported to target their victims elsewhere.

Today the Iraqi Prime Minister, Nouri al-Maliki, repeated his assertion that sectarian violence in Iraq was now virtually over. He told an audience of South Korean business leaders that recent attacks in the country were mainly the work of al-Qaeda and former Baath party members seeking a return to power.

The Iraqi Prime Minister, who is in South Korea and Japan trying to gather support for reconstruction work in the country, said he welcomed foreign investors with "open arms".

"Because of its abundance in resources such as oil and gas, Iraq has a great potential to become an advanced country," he said. "However, it is true that reconstruction is being delayed and all facilities are in ruins. But the Iraqi people are making utmost efforts to rise from the ashes."

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