Goodluck Jonathan, the Nigerian president, has imposed a "state of emergency" in three states in an attempt to curb the increasingly violent attacks by armed group Boko Haram, saying the level of violence called for "extraordinary measures".<br />The decision comes after a spate of attacks on security forces and government targets by armed group Boko Haram in its northeast stronghold this month.<br /><br />Al Jazeera's Yvonne Ndege reports from Nigeria.
