A large explosion has rocked the centre of the Iraqi capital, Baghdad, six days before elections are scheduled to take place. Officials said a suicide car bomb went off at a checkpoint near Prime Minister Iyad Allawi's party offices, located in the heavily fortified Green Zone. At least ten people to have reportedly been injured in the blast. Supporters of militant leader Abu Musab al-Zarqawi claimed responsibility for the attack in a statement on an Islamist website. On Sunday, Zarqawi - who tops Iraq's most wanted list - apparently declared war on the election.