Nigerian security forces knew four hours in advance about a planned raid by Islamist militants on a secondary school but did little to stop the attack in which more than 200 girls were abducted, Amnesty International said on Friday.
Boko Haram rebels stormed the school in the village of Chibok, near the Cameroonian border, on April 14, and kidnapped the girls, who had been sitting their final exams. Fifty have since escaped, but more than 200 remain with the insurgents.
The failure of security forces to protect the girls from abduction or find them after more than three weeks has sparked national and international outrage and led to protests in Abuja and the commercial capital Lagos.
Amnesty said it had independently verified information gleaned from interviews with various sources that troops at Nigeria's military headquarters in Maiduguri - 130 km from Chibok - were aware of the plot soon after 7 p.m. on April 14, close to four hours before Boko Haram began their raid.
"The fact that Nigerian security forces knew about Boko Haram's impending raid, but failed to take the immediate action needed to stop it, will only amplify the national and international outcry at this horrific crime," said Netsanet Belay, Amnesty International's Africa Director, in a statement.
"It amounts to a gross dereliction of Nigeria's duty to protect civilians, who remain sitting ducks for such attacks."
A lack of resources and fear of fighting the insurgents meant that reinforcements were not deployed to Chibok that night, the human rights group said.
"The small contingent of security forces based in the town - 17 army personnel as well as local police - attempted to repel the Boko Haram assault but were overpowered and forced to retreat. One soldier reportedly died," Amnesty said.
Nigerian officials were not immediately available for comment on Amnesty's allegations.
FEAR AND FATIGUE
Amnesty's statement came on the same day British experts arrived in Nigeria to advise the government on how to find and rescue the kidnapped schoolgirls. The United States, France and China have also offered to help the West African country.
Boko Haram's five-year-old insurgency is aimed at reviving a medieval Islamic caliphate in modern Nigeria, whose 170 million people are split roughly evenly between Christians and Muslims.
President Goodluck Jonathan has promised to find the abducted girls but has admitted he does not know where they are.
Amnesty said security and local officials repeatedly alerted the military commands in Damboa, 37 km away from Chibok, and Maiduguri between the evening of April 14 and early morning the next day.
It said civilian patrols in a village neighbouring Chibok, were among the first to raise the alarm after a large group of armed men entered their village on motorbikes and said they were headed to Chibok.
"There's a lot of frustration, exhaustion and fatigue among officers and (troops) based in the hotspots ... many soldiers are afraid to go to the battle fronts," Amnesty quoted a senior army officer as saying.
Abubakar Shekau, the leader of Boko Haram, which means "Western education is sinful", has threatened to sell the abducted girls "on the market".