BASRA: At least four people were killed and 20 wounded in an explosion in Iraq's southern city of Basra, police and hospital sources told Reuters on Tuesday.

Police are still investigating the cause of the blast, which took place in the city centre, near a main hospital. The explosion set fire to at least one vehicle and damaged a minibus.

One police source said that an initial investigation showed that a motorcycle rigged with explosives could have been the cause of the blast.