The Nigeria Police Is offering a $300,000 (£200,000) cash reward to anyone who can help locate more than 200 abducted schoolgirls.
They were kidnapped more than three weeks ago by armed Islamist militants from their boarding school in the north-eastern state of Borno.
Another eight girls were taken on Sunday from a village near the militants’ hideout in a nearby forest, while unconfirmed reports have it that another three girls have also been abducted in Borno.
A team of US experts has been sent to Nigeria to help in the hunt, reports the BBC.
Earlier this week, the Boko Haram group admitted that its fighters had abducted the girls in the middle of the night from their school in the town of Chibok on 14 April.
The group, whose name means “Western education is forbidden” in the local Hausa language, has staged a wave of attacks in northern Nigeria in recent years, with an estimated 1,500 killed in the violence and subsequent security crackdown this year alone.