A security expert says the personal security for former Japanese prime minster Abe Shinzo was inadequate, following his fatal shooting.

Abe was shot on Friday while delivering a speech on the street in the western prefecture of Nara.

Ito Koichi is a former police officer who once belonged to the Tokyo police's special unit, and is well-versed in security for high-profile figures.

He made the comment after analyzing footage showing the attacker wandering around with a bag and walking straight up to Abe.

Ito said that when observing such suspicious behavior, the person must be kept away even before asking questions and inspecting belongings.

He also pointed out that police officers failed to effectively coordinate with each other to make appropriate responses.