A Christian group on Saturday said 315 students and teachers were seized a day earlier in Nigeria's second mass school abduction in a week, as security fears mounted in Africa's most populous nation.

The early Friday raid on St Mary's school in Niger state in central Nigeria came after gunmen on Monday stormed a secondary school in neighbouring Kebbi state, abducting 25 girls.

The Christian Association of Nigeria said the new number came"after a verification exercise" following the early Friday mass kidnapping, and added that"The total number of victims abducted... is now 303 students and 12 teachers".

The number of students kidnapped is almost half of the school's 629 enrolled pupils.

Authorities in the nearby states of Katsina and Plateau have ordered all schools to close as a precautionary measure.

The Niger state government closed many schools and President Bola Tinubu cancelled international engagements, including attending the G20 summit in Johannesburg, to handle the crisis.

The two abduction operations and an attack on a church in the west of the country, in which two people were killed, have happened since US President Donald Trump threatened military action over what he called the killing of Christians by radical Islamists in Nigeria.

Nigeria is still scarred by the kidnapping of nearly 300 girls by Boko Haram jihadists at Chibok in northestern Borno state more than a decade ago. Some of those girls are still missing.

'Increased threat level'

The Niger state government accused the Catholic school of defying orders to temporarily close all boarding schools in parts of the state following an intelligence report of an"increased threat level" in areas bordering Kebbi.

Niger state police said its tactical units and the military were searching for the pupils. It said security agencies were"combing the forests with a view to rescue the abducted students".

Nigeria's president put security forces on high alert and sent defence minister Alhaji Bello Matawalle to lead the search for the Kebbi school girls.

His office said the minister had "experience in dealing with banditry and mass kidnapping", after he secured the release of 279 students aged between 10 and 17 who had been kidnapped from a secondary school in 2021 in northwestern Zamfara state.

In a separate attack on a church in western Nigeria on Tuesday, gunmen killed two people during a service that was being broadcast online. Dozens of worshippers are believed to have been abducted.

As Nigeria grapples with security challenges on several fronts, hostage-taking has spiralled nationwide and become a favoured tactic of bandit gangs and jihadists.

Although bandits have no ideological leanings and are motivated by financial gain, their increasing alliance with jihadists from the northeast has been a source of concern for authorities and security analysts.

Jihadists have for 16 years been waging an insurrection in the northeast with the aim of establishing a Caliphate.

The jihadist violence has killed more than 40,000 people and displaced around two million in the northeast since it erupted in 2019.