A roadside bomb has killed at least 21 people traveling to a wedding in the south of Afghanistan.About half a dozen people were also reportedly wounded in the attack. Police say those killed included women and children. They were traveling in a trailer and tractor when the homemade device went off in Helmand province. The blast came as new NATO secretary general Anders Fogh Rasmussen made his first official visit to Afghanistan after taking over the alliance. The former Danish prime minister pledged yesterday to increase security efforts ahead of the Afghan presidential election on the 20th August. Violence has reached an all time high in Afghanistan since the US led invasion in 2001, escalating dramatically following joint offensives this summer by British and American forces. The Taliban has vowed to attack this months presidential poll and has warned Afghans not to vote.