US Secretary of State Hillary Clinton has taken a tumble as she boarded a plane in Yemen.

Mrs Clinton was in the Arab country to discuss the fight against terrorism with President Ali Abdallah Saleh in Sanaa.

After climbing the steps to her plane, she slipped to her knees and had to be helped to her feet by an aide.

The cabin lights were swiftly dimmed to save Mrs Clinton from embarrassment but her fall had already been captured on film.

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.