An official said the girls were released through negotiations with the government
The girls were among 220 kidnapped in the northern town of Chibok in 2014 and this would be the largest group to be freed.
An official said the girls were released through negotiations with the government.
A military source said the girls were currently in Banki near the Cameroon border for medical checks before being airlifted to Maiduguri, the capital of Borno state.
The kidnappings sparked a global campaign #bringbackourgirls supported by then US First Lady Michelle Obama.
About 21 Chibok were released in October in a deal thrashed out by Switzerland and the International Red Cross.
A Nigerian government spokesman said a statement would be released soon giving exact details of the girls' release.
Nigerian President Muhammadu Buhari said last month that the government was in talks to secure the release of the remaining captives.
Additional reporting from IRN.