Guterres' reaction to the incident, which reportedly occurred in the early hours of Friday, came through his spokesman, Mr Stephane Dujarric.

"You will have seen the reports of a mass abduction of girls from a school in Zamfara in Nigeria.

"I can tell you that the Secretary-General condemns this in the strongest possible terms and calls for their immediate and unconditional release. 

"As we've said before, schools should always remain safe spaces to learn without fear of violence," Dujarric told newsmen in New York.

He said the Secretary-General would release a full statement on the incident 'shortly'.