The number of girls reported abducted by Islamist extremist sect Boko Haram in a new kidnapping incident in northern Nigeria rose to 11 Wednesday, according to local media.

Vanguard, a newspaper, cited local residents as it upped the number of kidnapped.

Nigerian media had originally reported Tuesday that eight girls had been kidnapped from the village of Waranbe, in the Gwoza local government area in Borno State.

The abductions come three weeks after Boko Haram, which means "Western education is sinful," kidnapped more than 200 schoolgirls from a boarding school in Chibok, in Borno State.

Boko Haram leader Abubakar Shekau threatened Monday to sell and enslave those girls. It remains unclear how many are still in captivity, as some have escaped since the initial kidnapping.

Nigerian President Goodluck Jonathan has accepted an offer of immediate help from the United States in tracking down and fighting the terrorists, U.S. officials said.

The UN Human Rights Office warned Boko Haram that its actions may be judged as crimes against humanity, a label for severe and systematic acts of violence.