KANO, (Nigeria): Boko Haram on Tuesday claimed it was behind the abduction of hundreds of students in northwestern Nigeria, in what appears to be a major expansion of the jihadist group's activities into new areas.

At least 333 students are still missing since the attack late Friday on the all-boys Government Science Secondary School in Katsina state - hundreds of kilometres (miles) from Boko Haram's stronghold in northeastern Nigeria.

"I am Abubakar Shekau and our brothers are behind the kidnapping in Katsina," the leader of Boko Haram said in a voice message. More than 100 gunmen on motorcycles stormed the rural school north of Kankara town, forcing students to flee and hide in the surrounding bush.