The United States has deployed surveillance aircraft in the search for the Nigerian school girls abducted by Islamist militant group Boko Haram even as experts have begun examining the outfit's latest video for clues.

Washington is also sharing commercial satellite imagery with Abuja to intensify the ongoing operation to locate more than 200 girls who remain in captivity a month after they were abducted from their school dormitory.

"We have shared commercial satellite imagery with the Nigerians and are flying manned ISR [intelligence, surveillance and reconnaissance] assets over Nigeria with the government's permission," an unnamed senior Obama administration official said, according to several news outlets.

In addition to that, the US is reportedly considering the deployment of unmanned drones for the mission.

The US sent about 30 officials from several law enforcement agencies to aid the anti-Boko Haram operation last week.

Meanwhile, forensic experts are examining the new video released by Boko Haram leader Abubakar Shekau in which he said all the captured teenagers have been converted to Islam. The video showed at least half of the missing girls in an undisclosed location.

"Our intelligence experts are combing through every detail of the video for clues that might help ongoing efforts to secure the release of the girls. We have no reason to question its authenticity," said US State Department spokesperson Jen Psaki.

Local reports suggest the location resembles the Samisa forest reserve.

The girls, who were seen wearing full-length hijabs, could be exchanged if the Nigerian government releases imprisoned Boko Haram members, the militant leader said in the video.

However, it is still uncertain whether the Abuja administration is willing to accept such an offer.