The Nigerian government says the militant group Boko Haram has agreed to a cease-fire and the release of more than 200 schoolgirls kidnapped by the militants in April.

Nigeria's highest-ranking military official, General Alex Badeh, announced the cease-fire agreement Friday. He ordered all of the country's military chiefs to abide by the deal.

The government expects the cease-fire agreement now in effect to lead to the release of the schoolgirls.

There has been no public comment from Boko Haram that any such deal has been reached.

Top Nigerian presidential aide Hassan Tukur tells VOA's Hausa service that the militants have agreed in principle to free the schoolgirls. He said negotiations in the past had not yet "yielded any positive results," but he is cautiously optimistic this time.

Boko Haram has terrorized Nigeria for the last five years as it tries to turn northern Nigeria into a conservative Islamic state. Bombings, gun attacks and other acts of violence have killed thousands of civilians and police.

The militants outraged the world when they stormed a school in the remote northeastern village of Chibok, kidnapping about 270 girls. Fifty-seven managed to escape, but more than 200 are still being held.

The cease-fire talks were held in Chad and involved Chad's president, Idriss Deby, and senior officials from Cameroon. It  marks a possible end to the five-year insurgency in which several thousand Nigerians have been killed.

Nigerian leader criticized

Jonathan has been criticized at home and abroad for Nigerian troops' inability to quell violence by the militants, seen as the biggest security threat to Africa's top economy and leading energy producer.

Boko Haram rebels are suspected of abducting dozen
Chibok schoolgirls who escaped the rebels prepare to meet with officials in Maiduguri, Nigeria, June 2, 2014.

Criticism intensified in mid-April, when dozens of Boko Haram fighters stormed a secondary school in the remote northeastern village of Chibok, kidnapping around 270 girls. Fifty-seven managed to escape.

In a video, the Boko Haram leader known as Abubakar Shekau threatened to sell the other girls as slave brides, vowing they would not be released until militant prisoners were freed from jail.

Boko Haram has said it is fighting to establish an Islamic state in Muslim-majority northern Nigeria.

The group has launched scores of attacks in the past five years, targeting markets, bus stations, government facilities, churches and even mosques.  Militants recently took over some towns in the northeast for what Shekau said in another video would be an Islamic caliphate.

The Nigerian military says that Shekau was actually an impostor and that the real Shekau was killed several years ago. It says the impostor was killed last month during a battle in the town of Konduga. 

VOA's Hausa service, correspondent Anne Look, and reporters Yusuf Aliyu Harande and Umar Farouk contributed to this report.