(Reuters) - A steady stream of mourners on Saturday visited the scene of former Japanese Prime Minister Shinzo Abe's assassination in the western city of Nara, an unusual act of political violence that has shocked the nation.

Japan's longest serving modern leader was gunned down while making a campaign speech on Friday morning by a 41-year-old man, in a deed decried by the political establishment as an attack on democracy itself. read more

On the final day of campaigning before Sunday's parliamentary election, a metal detector was set up at the site of Prime Minister Fumio Kishida's stump speech in a city southwest of Tokyo, an unusual security measure in Japan, along with increased police presence.

"I'm just shocked that this kind of thing happened in Nara," Natsumi Niwa, a 50-year-old housewife, said after offering flowers with her 10-year-old son near the scene of the killing at a downtown train station.

Abe, a conservative and architect of the "Abenomics" policies aimed at reflating the Japanese economy, inspired the name of her son, Masakuni, with his rallying cry of Japan as a "beautiful nation", Niwa said. "Kuni" means nation in Japanese.

Over 100 people were queuing to lay flowers at midday at a table featuring a photo of Abe giving a speech, with more arriving. Local officials were moving some of the offerings to create space.

A night vigil will be held on Monday, with Abe's funeral to take place on Tuesday, attended by close friends, Japanese media said. There was no immediate word on any public memorial service.

Police are scrambling to establish details of the motive and method of Abe's killer.

Tetsuya Yamagami, tackled and arrested immediately after the attack, told police he believed Abe was linked to a religious group he blamed for ruining his mother financially and breaking up the family, local media reported, citing police sources. Police have not identified the group.