The top US and Nato commander in Afghanistan is visiting the site of an airstrike where villagers reportedly died when American jets bombed two fuel tankers hijacked by the Taliban. General Stanley McChrystal travelled to inspect the site in northern Kunduz province today as Nato began a formal investigation into the attack in which up to 70 people died. It was unclear how many of the dead were militants and how many were villagers siphoning fuel from the trucks. Preventing civilian deaths has been a priority for General McChrystal since he took command in Afghanistan this year.