The head of Japan's hunters' association says the firearm used in the shooting attack on former Prime Minister Abe Shinzo may have been a self-modified gun.

Sasaki Yohei, head of Dainihon Ryoyukai, told NHK on Friday that the suspect is not a member of his organization.

He also denied the possibility of the firearm shown in news reports being a shotgun. He said a permit is required in order to possess a shotgun. Referring to the smoke the weapon in the attack reportedly emitted, he said an ordinary shotgun barely produces smoke.

He added that the firearm shown in news video is much smaller than an ordinary shotgun, which is about 140 centimeters long.

Sasaki said he has seen assorted types of guns abroad but has never seen one like the firearm shown in TV footage from the attack scene. He said he couldn't see where to load the bullets in the gun, which makes him assume that the weapon may be a very crude, self-modified gun.