KANO: A girl thought to be as young as seven killed herself and seven others in a suicide bombing in northeast Nigeria on Sunday as President Goodluck Jonathan conceded his government had initially underrated the Islamist extremist group Boko Haram. The attack on a market in the city of Potiskum, the commercial capital of Yobe state, was the latest in a string of suicide strikes in which children have been used. The initial death toll given by witnesses and hospital sources was six - the bomber and five others - but medical sources at the state-run hospital in Potiskum said later two of those injured had also died. Previous attacks have been blamed on Boko Haram. 19 people injured in the blast were taken to the hospital, a local vigilante leader, Buba Lawan, The bombing highlights the severe security challenges facing Nigeria in the run-up to presidential and parliamentary elections on March 28. During a swing through neighbouring Chad, Cameroon and Niger, French Foreign Minister Laurent Fabius on Sunday urged Nigeria to entirely commit itself to battling Boko Haram.