Investigative sources say police in Japan are examining an explosive device that did not go off tied to the attack on Prime Minister Kishida Fumio on Saturday.

They say police found the undetonated cylinder-shaped object near where a man allegedly hurled a bomb at Kishida, and are analyzing its mechanism, contents and yield.

Police also seized another object of a similar design that is believed to have blown up.

Kishida was at a campaign event at a fishing port in the western city of Wakayama when the attack occurred. The suspect, 24-year-old Kimura Ryuji, was arrested on the spot and sent to prosecutors on Monday.

He is reportedly refusing to answer questions from police and has remained silent.

Footage taken from an NHK helicopter shows investigators converging on a compound near a beach in Wakayama City on Monday in what appears to be a search related to the attack. Heavy machinery used by a bomb disposal team is also visible.

The object that apparently exploded after being thrown toward Kishida was found near a warehouse, about 40 meters from the blast site.

The devices are believed to be homemade. Police have seized tools and a substance thought to be gunpowder along with metal pipes from Kimura's home in the city of Kawanishi, Hyogo Prefecture.