by Aminu ABUBAKAR

Around 100 schoolchildren kidnapped from a Catholic school in Nigeria last month were handed over to state officials Monday, AFP reporters saw, though the fate of many others remains unknown.

The children -- many wearing football jerseys and girls in long robes -- were driven to the Niger State Government House in white buses escorted by a dozen military vans and armoured vehicles.

In late November, the Christian Association of Nigeria (CAN) said 315 students and staff were kidnapped from St Mary's co-educational boarding school in north-central Niger state.

The attack came as the country buckled under a wave of mass abductions reminiscent of the infamous 2014 Boko Haram kidnapping of schoolgirls in Chibok.

It is unclear how many remain held by the attackers. Some 50 escaped immediately afterwards meaning that, with the 100 released Monday, there would be about 165 thought to remain in captivity. 

A statement Monday from President Bola Tinubu put the remaining being held at 115.

The children handed over Monday were to undergo medical checks before being reunited with their parents, Niger state Governor Umar Bago said.

Theresa Pamma, a UNICEF official, said "we all know that, for being over two weeks in captivity, those children certainly need some help", including mental health care.

Bago shook hands with some of the children and led them into a hall where an emir and local officials received them.

It was unclear how the students' release was secured.

Kidnappers unknown

According to a list of the released children seen by AFP, most of those freed are aged between 10 and 17. The school catered for children as young as nursery-school age.

It was unclear who seized the children from their boarding school in the remote rural village of Papiri.

"Our security agencies, working with the governors, must prevent future kidnappings. Our children should no longer be sitting ducks for heartless terrorists," Tinubu said in a statement.

Though kidnappings for ransom are a common way for criminals and armed groups to make quick cash, a spate of mass abductions in November put an uncomfortable spotlight on Nigeria's already grim security situation. 

The country faces a long-running jihadist insurgency in the northeast, while armed "bandit" gangs attack and loot villages in the northwest.

In November, assailants across the country kidnapped two dozen Muslim schoolgirls, 38 church worshippers and a bride and her bridesmaids, with farmers, women and children also taken hostage.

The kidnappings came as Nigeria faces a diplomatic offensive from the United States, where President Donald Trump has alleged that there were mass killings of Christians that amounted to a "genocide". 

The Nigerian government and independent analysts reject that framing, which has long been used by the Christian right in the United States and Europe. 

The religiously diverse African country of 230 million people is the scene of myriad conflicts that have killed both Christians and Muslims.

Though there was not a breakdown of the kidnapped pupil's religions, St Mary's "accommodates Christians and Muslims" as students, Daniel Atori, a spokesman for CAN in Niger state, told AFP Saturday.

US Representative Riley Moore, who has seized on accusations of the mistreatment of Christians, said on social media Monday he met with Nigerian security officials as part of a congressional delegation visit to the country.

The rescue of the 100 children is "a positive demonstration of the government's increasing response to the security situation", he said.