No-one in the Nigerian city of Maiduguri knows who to be afraid of most, a group of Islamic militants known as Boko Haram or the police.

The sect, thought to have been eliminated after a brutal uprising in 2009 in which hundreds of people were killed, is back and its members want revenge.

For the past five months they have been fighting a guerrilla war, killing policemen and people they believe helped the security services in the fight against them.

Residents of the city in the far north-east of Nigeria are trapped in the middle and anyone speaking about the sect does so nervously.