<p><br /> US Secretary of State Hillary Clinton has taken a tumble as she boarded a plane in Yemen.<br /> </p><p><br /> Mrs Clinton was in the Arab country to discuss the fight against terrorism with President Ali Abdallah Saleh in Sanaa.<br /> </p><p><br /> After climbing the steps to her plane, she slipped to her knees and had to be helped to her feet by an aide.<br /> </p><p><br /> The cabin lights were swiftly dimmed to save Mrs Clinton from embarrassment but her fall had already been captured on film.<br /> </p><p><br /> During the surprise visit to Yemen, Mrs Clinton urged leaders to step up security co-operation with the US to combat the continuing threat from an al-Qaeda faction based in the country.<br /> </p>
