Nigerian security forces failed to act on an advance warning about a raid by the Islamist militant group Boko Haram on a school that led to the abduction of more than 200 girls last month, Amnesty International said Friday.

Nigeria’s military headquarters in the Borno state capital, Maiduguri, became aware of the imminent attack on Chibok at just after 7 p.m. April 14, said Amnesty, which cited “credible sources.” By midnight, the attack was underway.

The abduction, which came on the same day as the worst-ever bomb attack on the capital, Abuja, has sparked international criticism. Abubakar Shekau, the leader of Boko Haram, which means “western education is a sin” in the Hausa language, has claimed responsibility for the April 14 abduction of 276 girls from their dormitories in Chibok in the northeast.

Bloomberg News Service