THE United States and Britain warned of a possible terrorist attack in Nigeria's federal capital Abuja, especially aimed at government buildings, places of worship and schools, among other targets. Nigeria is fighting an Islamist insurgency mainly in the northeast, but in July the Islamic State claimed responsibility for a raid on a prison in Abuja, which freed around 440 inmates, raising fears that insurgents were venturing from their enclaves. The U.S. Embassy in Nigeria said "there is an elevated risk of terror attacks in Nigeria, specifically Abuja" and added that shopping malls, law enforcement facilities and international organisations were among the…