The radical Islamist group Boko Haram released a new video Monday featuring what appears to be dozens of the Nigerian schoolgirls who were kidnapped in mid-April.

In the video, around 100 of the 230 girls who were abducted are seen wearing hijabs, traditional female Islamic garb, and praising Allah at an undisclosed location. It is not clear where the rest of abducted girls were taken, reports USA Today.

The video was released to French newswire Agence France Presse (AFP) and the Associated Press, although it has not been confirmed as authentic. It comes weeks after militants seized about 230 girls at a high school in the Chibok area of northeastern Borno on April 14, reports The Guardian.

"A total of 230 parents registered the names of their daughters who were missing on the day of the kidnap," said Asabe Kwambura, principal of the Government Girls Secondary School, according to CNN. "From my records, 43 girls have so far escaped on their own from their kidnappers. We still have 187 girls missing."

A man in the video, who identifies himself as Boko Haram leader Abubakar Shekau, said that the Christians girls have converted to Islam. He also offered to trade them if members of Boko Haram are released from prison by the government.

"By Allah, these girls will not leave our hands until you release our brothers in your prison. It is now four years or five years that you arrested our brethren and they are still in your prison," Shekau said in the video. "(The girls) are staying (with us). We won't ever release them until our brethren are released."

He added that he still plans to sell them into slavery.

In response, some Nigerian officials insisted Monday that the man in the video can't be confirmed to be Boko Haram leader Abubakar Shekau, who is thought to be dead. However, at a later briefing, the director of the National Orientation Agency said negotiations could be an option to rescue the kidnapped girls.

"All options are on the table," Director Mike Omeri said.

A senior administration official also told CNN that U.S. officials believe the video is authentic.

"Our intelligence experts are combing over every detail of the video for clues that might help in the ongoing efforts (to) secure the release of the girls," the official said.