The Islamist militant sect Boko Haram has claimed responsibility for last month's kidnapping of hundreds of schoolgirls in northern Nigeria.
In a video sent to news agencies Monday, Boko Haram leader Abubakar Shekau says "I abducted your girls," and also vows to "sell them in the marketplace."
Gunmen abducted the girls from a school in the town of Chibok, Borno state on April 14. Nigerian authorities say some escaped, but 276 are still missing.
On Sunday, Nigerian President Goodluck Jonathan ordered top security officials to do everything possible to secure the girls' release.
In a televised appearance Sunday, Mr. Jonathan promised "... anywhere the girls are, we will surely get them out."
``We promise that wherever these girls are, we will surely get them out, one good thing that I'm a bit happy and I believe most Nigerians are happy is that there is no story that any of them has been hurt in terms of injured or that."
The president described it as a "trying" and "painful time" and pleaded for the cooperation of parents, guardians and local communities in the rescue efforts.
Unconfirmed reports say some of the girls have been "married" to their captors, while others allegedly have been moved across the border into Cameroon and Chad.
Meanwhile, Nigerian police have arrested the leader of a protest in which demonstrators pressured the government to locate the girls. Naomi Mutah Nyadar was taken into custody late Sunday after she and other advocates for the girls met with the president's wife.