Boko Haram leader makes demands in new video

Islamist militants Boko Haram have released a video apparently showing about 130 girls kidnapped from a school in northern Nigeria on 14 April.

Boko Haram leader Abubakar Shekau also appeared in the video and said the children would be held until all imprisoned militants had been freed.

The group has abducted more than 200 girls in recent weeks and previously threatened to sell them.

The BBC's World Affairs Editor John Simpson reports.