United States America have agreed using the FBI to help Nigeria find the more than 200 missing schoolgirls abducted by terrorist group Boko Haram.
Attorney General Eric Holder said the US was sending FBI agents to trace the girls as grief-stricken families took to the streets to protest over the inaction of the Nigerian government and military to find their missing daughters.
In a video obtained by French news agency, AFP, Boko Haram leader Abubakar Shekau said: "I abducted your girls. I will sell them in the market, by Allah."
At least 276 youngsters were taken from their school in Chibok, in the state of Borno, north Nigeria, by the Islamist militants. They abducted the teenagers, who had been taking their West African Examinations Council exams, into trucks and disappeared into a remote area along the border with Cameroon.
Nigerian President Goodluck Jonathan said: "We promise that anywhere the girls are, we 'll surely get them out."
He said he had asked the US, Britain, France and China for help to fight against Boko Haram and dismissed claims his government was negotiating with the group.
It is believed that the girls who were taken from a school in the village of Chibok on 14 April have already been sold as brides for as little as £7 ($12), according to the girl's relatives.