Shinzo Abe assassination | 'Undeniable flaws' in ex-Japan PM's security: Police

"I believe it is undeniable there were problems with the guarding and safety measures for former prime minister Abe," Tomoaki Onizuka, Nara prefecture police chief, was quoted by AFP.

There were 'undeniable' flaws in the security cover provided to ex-Japan prime minister Shinzo Abe - assassinated in the city of Nara after the shooter got close to him and fired twice from a homemade shotgun - the head of police said Saturday morning. "I believe it is undeniable there were problems with the guarding and safety measures for former prime minister Abe," Tomoaki Onizuka, Nara prefecture police chief, was quoted by AFP.

An attendee holds a tablet computer displaying a photograph of former Japanese Prime Minister Shinzo Abe during an election campaign event in Yokohama, Japan.  (Bloomberg)

Onizuka said a thorough probe would be conducted to clarify what happened, but did not provide any information regarding specific shortcomings in Abe's security plan.

"In all the years since I became a police officer in 1995, in my career that stretches more than 27 years, there is no greater remorse, no bigger regret than this," an emotional Onizuka said.

In Japan, political security details can be relatively lax, particularly during election campaigns when candidates and leaders make roadside appearances and speeches. Japan also has a low rate of violent crime and some of the strictest gun control laws in the world.

Nevertheless, considering Abe's stature - a two-time former prime minister and one of the country's most recognised figures - questions have been asked about whether there were enough measures to protect the country's longest-serving leader.

Fumikazu Higuchi, a former Kyoto Prefecture investigator, was cited by the Associated Press as saying footage suggested sparse security, certainly insufficient for a former PM.

A 41-year-old suspect has been identified as Abe's assassin - Tetsuya Yamagami - who claims to be a former member of the Maritime Self-Defense Force.

Police say Yamagami has admitted to shooting Abe with the homemade gun.

"The suspect stated he held a grudge against a particular organisation and that he committed the crime because he believed former prime minister Abe had a connection to it."

The name of this organisation has not been divulged but local media said it was a religious group. Yamagami's original plan was to kill the head of this group but he shot Abe because he believed the ex-PM promoted the group in Japan, Kyodo News reported.