Attack 'took Nigerian troops by surprise'
Nigeria's defence minister has told the BBC that last week's attack by Boko Haram caught his troops by surprise.
Bello Halliru Mohammed said that despite a large military presence in northeastern Nigeria, fighters from the Islamist group had given his men the slip.
A week ago more than a hundred people died when Boko Haram launched an assault on the town of Damaturu.
The BBC's correspondent in Nigeria Jonah Fisher reports.