A suspicious package that prompted the cancellation of a hearing Monday for the man accused of murdering former Prime Minister Shinzo Abe contained only a petition, and no explosives, sources have said.

The cardboard box set off a metal detector at the Nara District Court in the city of Nara but was later found to have contained a petition seeking leniency for the defendant, Tetsuya Yamagami, the sources said.

Yamagami stands accused of fatally shooting Abe with a handmade gun during an election stump speech in Nara in July last year. The incident sent shockwaves across Japan and the world.