Around 1,000 students have been kidnapped in the west African country since December after gangs started to hit schools. Most have been released after negotiations, but scores are still being held in forest camps.
Nigerian gunmen have freed the remaining pupils from more than 100 kidnapped from an Islamic seminary in northwestern Niger state nearly three months ago, the school's head teacher said.
Heavily armed criminals snatched 136 pupils from the seminary in Tegina on May 30 in one of a series of mass abductions targeting schools and colleges in Nigeria since December.
Six of the pupils died in captivity and another 15 escaped in June, according to school officials.
"The pupils have all been released. We are now conveying them home," Abubakar Alhassan told AFP by telephone.
"I can't give you an exact number now. We will have to screen them when we get home. But none of the pupils is in captivity."
He did not give any details about how the pupils were released. But one of the parents, Fati Abdullahi, whose 18-year-old daughter and 15-year-old son were among the captives, confirmed the pupils were free.
Surge in attacks
Northwest and central Nigeria have seen a surge in attacks, looting and mass abductions by criminal gangs known locally as bandits. But gangs this year began targeting schoolchildren and students as a way to squeeze out more ransom payments.
Gunmen who kidnapped more than 100 students from a Baptist high school in northwestern Kaduna State released 15 more of those hostages after collecting ransom, a representative of the families said on Sunday.
Around 1,000 students have been kidnapped since December after gangs started to hit schools. Most have been released after negotiations, but scores are still being held in forest camps.