Islamist rebels duped dozens of Nigerian schoolgirls into thinking they were soldiers come to evacuate them before abducting more than 100 in their latest anti-government raid, one of the survivors said yesterday.

Gunmen suspected of being members of the radical Islamist movement Boko Haram swooped on Chibok town in Borno state and on its nearby all-girls government secondary school late on Monday, calling on the students to leave their beds in the hostel.

The mass abduction of schoolgirls aged between 15 and 18 has shocked Nigeria and shown how the five-year-old Boko Haram insurgency has brought lawlessness to swathes of the arid, poor North East, killing hundreds of people in recent months.

It occurred the same day a bomb blast, also blamed on Boko Haram, killed 75 people on the edge of the capital, Abuja, stirring fears of violence spreading from the north of Africa's number-one oil producer.

The Chibok students, who had returned to sit final-year-certificate exams, initially obeyed the armed visitors, thinking they were Nigerian troops there to protect them.