Nigeria's President Bola Tinubu on Wednesday declared a "nationwide security emergency" as the country scrambled to respond to a wave of mass kidnappings that have seen hundreds of people, mostly schoolchildren, captured in a week.

"This is a national emergency, and we are responding by deploying more boots on the ground, especially in security-challenged areas," Tinubu said in a statement.

Within days, assailants across the country kidnapped two dozen Muslim schoolgirls, 38 worshippers, more than 300 schoolchildren and teachers from a Catholic school, 13 young women and girls walking near a farm, and another 10 women and children.

Dozens have been rescued and others escaped but 265 children and their teachers seized from a Catholic boarding school in the country's Niger state on Friday are still missing.

"In view of the emerging security situation, I have decided to declare a nationwide security emergency and order additional recruitment into the Armed Forces," Tinubu said.

At the weekend he ordered a redeployment of police VIP bodyguards to core policing duties, and has ordered the hiring of another 50,000 new police recruits.

According to the European Union Agency for Asylum (EUAA) more than 100,000 of the estimated 371,000-strong force were previously assigned to protect politicians and VIPs.

In addition to a 16-year jihadist insurgency raging in the northeast, Nigeria is plagued by persistent insecurity, with frequent kidnappings for ransom.

The first mass abduction to shock Nigeria was in 2014 when the jihadist group Boko Haram kidnapped 276 teenage girls in Chibok, in the northeast, sparking an international outcry.

Since then thousands of kidnappings have occurred. Some go unreported. (AFP)