Christian girls in northern Nigeria are increasingly at risk of abduction by Muslims who are then forcing them to renounce their faith. 

Professor Daniel Babayi, of the Northern Christian Association of Nigeria, told Barnabas Fund that Christian girls below the age of 18 were being targeted.

The girls are held in the homes of Muslim leaders but when Christians report this to the police, they say there is nothing they can do.

"The police have become very helpless.  In some instances, they are part of the conspiracy," said Professor Babayi. 

Last year, militant Islamic group Boko Haram threatened to kidnap Christian women as part of "new efforts to strike fear into the Christians of the power of Islam", Barnabas reports.

Boko Haram has stated its intention to eradicate Christians from northern Nigeria and implement a strict interpretation of Sharia law across the region. 

The group has repeatedly attacked Christian communities and churches, most recently killing 40 at a boarding school in Yobe state on 6 July.  A dormitory was set alight in the attack and those fleeing gunned down. 

Last month, an attack on a secondary school in Yobe and another school in Borno left 16 students dead.  

Barnabas Fund added that Boko Haram was recruiting unschooled and unemployed children, sometimes by force.