Security fears

Many children were returning to school for the first time after the Muslim festival of Eid al-Adha.

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Twenty-five children were among the wounded, two hospital officials said.

The officials spoke on condition of anonymity because they were not authorised to release the information.

The blast partially toppled a brick wall in front of the school, leaving a crater that quickly filled with muddy water, apparently from a broken water line.

The attack comes a day after the Iraqi parliament passed a new electoral law paving a way for the general elections in February.

Iraqi and US military officials have expressed concern about a possible spurt in attacks aimed at destabilising the government before next year's elections.

On Monday, gunmen stormed a checkpoint near Tarmiyah, north of Baghdad, killing five members of an anti-al-Qaeda group, police said.

The men were members of the Sunni Awakening Council, one of many Sunni groups that have begun taking on al-Qaeda in Iraq.

There are an estimated 2.5 million Shia living in Sadr City, a stronghold of Shia leader, Muqtada al-Sadr, known for his anti-US stance.