At least 12 people have been killed and dozens wounded in a roadside bomb attack in Afghanistan. A local police chief was the Taliban’s intended target when passers by, including a woman and child, got caught in the blast. The device exploded in the western city of Herat. Insurgent attacks have escalated across Afghanistan in the run up to the country’s presidential elections.The Taliban have threatened to disrupt the poll, which is seen as a key test for the NATO alliance, and have called on Afghans to boycott the ballot. Over the weekend nine foreign soldiers, including six Americans, were killed in the south and east of Afghanistan.