Japanese police say they have arrested a 16-year-old boy on suspicion of trying to manufacture a bomb to blow up his classmates.

Police found materials and ingredients to make hand-made bombs at his home in the northern city of Sapporo, a police spokesman said Thursday.

"Police confiscated explosive powder and some chemical substances from his house," he said.

Jiji Press reported that police seized some 50 items — such as screws and rivets — which would have been enough to make explosives as lethal as those used in the London attacks in 2005.

The boy reportedly got tips from the Internet on how to make bombs.

The high school student had been arrested earlier this month for allegedly sending a threatening message to a classmate's cell phone.

"I'm the killing god," the boy said in the message, according to police.

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