A leader of Boko Haram offers to release more than 200 schoolgirls kidnapped last month if the Nigerian government releases prisoners.
The Islamist rebel group has released a new video from an undisclosed location, which could not be independently verified by Reuters.
A clip from YouTube shows about 100 girls wearing full veils and chanting.
(SOUNDBITE) (Arabic) BOKO HARAM LEADER ABUBAKAR SHEKAU SAYING:
"By Allah, these girls will not leave our hands until you release our brothers in your prison. You took our brothers four or five years ago and now they are in your prisons - you do many things, and now you talk of these girls. We will not let them go until you release our brothers. We will not let them go until you release our brothers."
Authorities in Nigeria are currently holding hundreds of suspected Boko Haram militants.
There was no immediate reaction from authorities to the new video but one senior official said the government was studying the situation.
The abduction of the schoolgirls last month as they slept in their school dormitory has provoked global outrage.