Baghdad: An explosion outside an elementary school in a Shiite district of Baghdad killed at least eight people Monday, as Iraqi officials considered delaying national elections until at least February.

The blast occurred in the Shiite district of Sadr City, where large-scale attacks have been infrequent because of tight security by US and Iraqi forces as a well as the neighbourhood's own guards. Police and witnesses gave conflicting information about whether the blast was caused by a bomb, a rocket or an exploding weapons cache.

Among the dead were six children between the ages of 6 and 12, and 41 people were wounded, said officials from the police and Interior Ministry. Twenty-five children were among the wounded, two hospital officials said.

The officials all 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.

Inside at least one classroom, windows were blasted out and shards of glass were strewn over desks. Blood stained the wooden desks and books. Many backpacks were tossed about the room.

Sadr City is home to an estimated 2.5 million Shiites and is a stronghold of anti-American cleric Moqtada Al Sadr.

In 2008, militants there poured rocket fire onto the Green Zone during the last major fighting in the city. Al Sadr's order to his militia fighters to ceasefire has been cited by the US military as a key factor in a steep drop in violence nationwide, along with a US troop buildup and a Sunni revolt against Al Qaida in Iraq.