Uk-born American journalist Luke Somers and South African teacher Pierre Korkie have been killed by al-qaeda militants in Yemen during a failed rescue bid. Saturday's operation was carried out by joint u.s and Yemeni special forces in the southern Shabwa region. US president Barack Obama condemned the "barbaric murder" of both hostages who were being held by militants from al-qaeda in the Arabian Peninsula , regarded by the US as one of the deadliest offshoots of al-qaeda.