Nigerian President Bola Tinubu on Wednesday declared a sweeping security emergency as the country confronts a sharp rise in large-scale abductions.

"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.

In just a week, assailants kidnapped 25 schoolgirls, 38 worshippers, 315 school children and teachers, 13 young women and girls walking near a farm, and another 10 women and children -- across parts of the country.

Dozens have been rescued, others escaped but more than 265 children and their teachers seized from a 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," he said.

At the weekend he ordered a redeployment of police VIP bodyguards to core policing duties, and approved the recruitment of 30,000 additional officers.

He has also ordered the hiring of another 20,000 officers - taking the total to 50,000 new police recruits.

Nigeria has suffered a string of abductions of schoolchildren since Islamist group Boko Haram kidnapped 276 girls in Chibok in the restive northeast in 2014, sparking an international outcry.