Insurgents strike at heart of America's power in Baghdad

Bombers in Baghdad took the war to the very heart of US power in Iraq yesterday when two blasts inside the supposedly impregnable Green Zone killed 10 people, four of them Americans, and injured 20.

Bombers in Baghdad took the war to the very heart of US power in Iraq yesterday when two blasts inside the supposedly impregnable Green Zone killed 10 people, four of them Americans, and injured 20.

Tawhid and Jihad, a group led by the Jordanian Abu Musab al-Zarqawi, claimed responsibility. Last night US forces launched a major offensive on Fallujah, where the militant leader is believed to be based. The town was pounded from the air by warplanes and helicopter gunships and heavy artillery and tanks on the ground. Two US Marine battalions began to advance into the town from the north and east.

Loudspeakers were used urging insurgents to lay down their weapons "because we are going to push into Fallujah".

The suicide attacks in the Green Zone are viewed as a huge propaganda boost for the insurgents. It is the most protected 10sq km in the country and home to the US and British embassies and Iraq's interim government.

The Iraqi interim government threatened to declare war on Fallujah. The National Security Adviser, Qassem Dawoud, said: "This cowardly act will not go unpunished. We shall strike them ... we shall smash them."

Earlier in the day an American soldier had been killed and two others injured in a roadside blast in Baghdad.

The four dead Americans in the Green Zone are believed to be private security contractors, and the injured included soldiers. The bombs had been carried in by hand despite a security regime that includes repeated stop and searches. One of them exploded at the Green Zone Café, where an explosive device was found and defused only last week. Western military sources stated that yesterday's bombs are likely to have been brought inside the area in parts and then assembled.

The area had come under mortar attack in the past. But this was the first time the militants had succeeded in carrying out an attack with so many casualties. It came on the eve of the Muslim holy month of Ramadan, which is expected to see an upsurge in the number of attacks, similar to the same time last year.

The first bomb exploded at just after 1pm. Three people died and three were injured in the first blast at a mock souk in the heavily fortified compound. Two more were killed in a second explosion at the café, a popular attraction for off-duty soldiers and Western civilians, five minutes later. Lieutenant-Colonel James Hutton, of the US army, confirmed that the bombers had been able to carry in their explosive devices.

Broken glass, twisted metal and dismembered body parts lay in pools of blood on the café floor. A survivor said: "People were screaming, they were stampeding trying to get out."

A member of staff at the American-run Ibn Sena Hospital inside the zone said: "There are body parts everywhere. At the moment we have eight dead, but this may rise. We have several wounded."

After the discovery of the bomb outside the café, the British embassy warned its staff not to use local shops and restaurants. Yesterday the US embassy extended the same message to its nationals. Foreign residents in the zone, especially women, have already been advised not to go out by themselves after dark.