The hunt for the kidnapped girls has entered a new phase, with Nigerian soldiers moved to the country’s border with Cameroon.
Soldiers have also been stationed near the borders with Chad and Niger.
Boko Haram insurgents are believed to be operating from these countries because of loose border security.
The kidnapped girls are said to be in the Sambisa forest which is close to the Cameroonian border.
Defence spokesman Major General Chris Olukolade said on Saturday night that two divisions of the Nigerian army have been posted to the borders.
“The facilities of the Nigerian Army signals as well as all the communication facilities of the Nigerian Police and all the services have been devoted into coordinating this search,” Olukolade said in a statement.
“The major challenge remains the fact that some of the information given here turned out in many occasions to be misleading. Nevertheless, this will not discourage the collaborative efforts that are ongoing.”
Olukolade said the air force has flown more than 250 sorties and that a multinational task force has also been activated and surveillance equipment is deployed in support of 10 search teams.
He denied reports of any arrests being made or that some of the girls had been found.
Nigeria’s search for the missing girls is being supported by many countries, including the US, UK, France and China.