An explosion rocked the Iraqi parliament in Baghdad yesterday and there were many casualties, a Reuters witness said.

He said the blast appeared to take place inside a restaurant inside the building at a time when many members of parliament were having lunch. The parliament building is located in the heavily fortified Green Zone in Baghdad.

Earlier, a truck bomb killed at least seven people on a key bridge in northern Baghdad, destroying most of the steel structure and sending several cars plunging into the River Tigris below, police said.

Two main sections of the Sarafiya bridge, a main artery linking east and west Baghdad, collapsed into the river. One army officer on the scene said explosive charges might have also been used to bring down a bridge that local residents said was built by the British in the early 1900s.

Among the dead were four policemen who drowned after their car toppled into the river's muddy waters, police said.

US and Iraqi forces launched a security crackdown in the capital two months ago that has reduced death squad killings, but car and truck bombs still kill and wound scores.

The destruction of the bridge will cause major disruption in northern Baghdad. Two other bridges across the Tigris in that part of the capital are shut for security reasons while another is regarded by many residents as too dangerous to use.

Conspiracy to isolate Baghdad

?There is a conspiracy to isolate the two halves of Baghdad,? parliament Speaker Mahmoud Mashhadani, an outspoken Sunni politician, told lawmakers. A dozen bridges cross the Tigris in Baghdad, linking the east and west of the city.

Since the bombing of a revered Shi'ite shrine in the town of Samarra in February 2006, a wave of sectarian violence has reshaped the fabric of this once mixed city. Sunnis mainly live on the west side of the river and Shi'ites on the east.

Police said seven people had been killed in the bridge blast. They said up to 22 people were wounded. At least five cars had fallen into the river, including the police vehicle.

The Baghdad security operation is regarded as a last-ditch attempt to halt Iraq's slide into civil war between majority Shi?ites and minority Sunni Arabs who were dominant under Saddam Hussein. US President George W. Bush is sending 30,000 more troops to Iraq, mainly to help with the Baghdad offensive.

Around 100,000 American and Iraqi forces are already in the capital for the push and all reinforcements should arrive by the end of May.

Dean YATES

OVERTIME?

Army extends Iraq tours to 15 months

■ Stretched thin by four years of war, the army is adding three months to the standard yearlong tour for all active-duty soldiers in Iraq and Afghanistan, an extraordinary step aimed at maintaining the troop buildup in Baghdad. The change, announced Wednesday by Defense Secretary Robert Gates, is the latest blow to an all-volunteer Army that has been given ever-shorter periods of rest and retraining at home between overseas deployments Rather than continue to shrink the at-home intervals to a point that might compromise soldiers? preparedness for combat, Gates chose to lengthen combat tours to buy time for units newly returned from battle.

The longer tours will affect about 100,000 soldiers currently in Iraq and Afghanistan, plus untold thousands more who deploy later. It does not affect the Marine Corps or the National Guard or Reserve. ?Our forces are stretched, there?s no question about that,? Gates said. The extended tours are a price the army must pay to sustain the troop buildup that President Bush ordered in January as part of his rejiggered strategy for stabilizing Baghdad and averting a US defeat. Troop levels are being boosted from 15 brigades to 20 brigades, and in order to keep that up beyond summer the army faced harsh choices : either send units to Iraq with less than 12 months at home, or extend tours.