U.S. Fears Kidnapped Nigerian Girls Taken Out of Country

The United States said Monday that it is concerned that many of the 276 Nigerian schoolgirls kidnapped in northern Nigeria three weeks ago have been moved out of the country.

State Department spokeswoman Marie Harf shared Washington's assessment after local officials in northeastern Nigerian told Agence France Presse the girls had likely been taken to nearby Chad or Cameroon.

The Islamist militant group Boko Haram has claimed responsibility for taking the girls from school, and its leader Abubakar Shekau declared his plan to sell them as slaves in a video released Monday.

"Many of them have likely been moved out of the country to neighboring countries," Harf said, responding to reporters' questions as news of the abduction began to climb up the world news agenda.

Harf said Washington provides Nigeria with "counter-terrorism assistance" in the form of intelligence sharing and was standing by to assist "in any way we think that is appropriate."