One bomb triggered a massive blaze at a petrol station

Hospital sources said the number of casualties from the attacks was likely to rise.

Earlier, a woman died when a US helicopter fired rockets at a house in the mainly Shia Sadr City area.

The military also announced that four US soldiers and a marine were killed in attacks by insurgents on Wednesday.

Three of the soldiers were killed when a roadside bomb exploded near their patrol south of Baghdad, while another was shot dead in the south-west of the capital.

The marine died of wounds he sustained in armed clashes in the central Iraqi city of Falluja.

Air strike

In Sadr City, the father of Ikhlas Abd al-Hussein said his 20-year-old daughter had been killed when the helicopter fired a missile at her house, blasting a hole through the roof.

Abd al-Hussein Shanuf said another woman and a two-year-old child had also been injured.

One report attributed to a US spokesman said four people had been killed in the air strike.

Although the US military insisted it had been hunting a Sunni Islamist militant, many residents believed the real target had been members of the Mehdi Army, the militia of the Sadr City-based radical Shia cleric Moqtada Sadr.

Iraqi Transport Minister Salam al-Maliki, a representative of Mr Sadr, condemned the attack and demanded compensation for the victims.

"These military operations aim at weakening the supporters of the Sadrist movement, are considered provocative and represent a clear violation against the security situation in the country," he told the Associated Press news agency.

In other developments, a police intelligence officer responsible for an area south of Basra was wounded and his driver killed in an assassination attempt.