Four car bombs shook Baghdad after dawn on Thursday, killing at least 17 people and wounding dozens in the second wave of attacks within hours, police said.

On Wednesday evening, car bombs in a mainly Shia district of the city killed 18 people, after a day of talks in Brussels between the new Shia-led government, its US backers and other nations.

Despite a month-long crackdown by US and Iraqi troops and police in Baghdad, the resistance and other groups have mounted major attacks on three days this week, while lower-level violence is keeping up pressure on all security forces.

Police said a car bomber killed three police officers and seven civilians when he drove at their patrol in the central commercial district of Karrada about 7am (0300 GMT). A second, similar attack killed seven civilians, they said.

Two other cars exploded in the same area, several minutes apart, one near a Shia mosque. Police and medical sources put the number of wounded at 23 to 50.

Internet statement

The Army of Ansar al-Sunna said in an internet statement it had carried out the three bombings in a joint operation with the Islamic Army in Iraq and the Mujahidin Army.

It said it had exploded a car bomb at a convoy of Iraqi police and when other police vehicles gathered around the blast site, "they entered into the mujahidin ambush where two other cars were detonated". The group later said it exploded a fourth car against Iraqi police in the same area, killing seven.

About 1200 people, including around 120 US troops, have been killed in political violence since the Shia-led government was formed two months ago.

In addition to the 18 dead, Wednesday night's coordinated bomb attacks wounded 48 in the Shia Shola district of Baghdad, police said. The area's main street was devastated.

Al-Zarqawi statement

Abu Musab al-Zarqawi, claimed responsibility for Wednesday's "Sunni reprisal raid".

Al-Zarqawi's group said an Iraqi and four foreign fighters were killed by US forces at a house in Baghdad's Jamiaa area, where residents heard a fierce battle overnight.

PHOTO CAPTION

A US soldier guards a checkpoint outside Baghdad. (AFP)