Over 2.1 million people are internally displaced in northeast Nigeria after a spike in a six-year insurgency by the Boko Haram group, the International Organisation for Migration said Friday, revising a previous figure of 1.5 million.

"The recent spike in attacks by insurgents triggered the increase," the IOM said, referring to stepped up attacks by the hardline Islamist group in recent months that have left more than 1,000 dead since May 29 when President Muhammadu Buhari came to power.