The chief of Japan's National Police Agency on Thursday said he would resign to take responsibility over the shooting of former Prime Minister Shinzo Abe in July.

Itaru Nakamura is the most senior official to stand down since the fatal shooting of Abe — which has been blamed on security failings — shocked the country.

What did the police chief say?

Nakamura made his announcement at a press conference that detailed findings of an investigation into flaws that led to Abe's July 8 assassination in Nara, western Japan.

"As we scrutinised and reflected on the incident, we decided to start over and overhaul our security system," Nakamura said.

"In the process of verifying our new security plan, we have come to realize that our security duties would need a fresh start. To mark our fresh start with a new security plan, it is only natural for us to build a new organization."

Nakamura had previously stated regret over the failure of police in protecting Abe during his appearance at a campaign rally, where he was fatally shot. He also admitted there were faults in the protection plan.

What did the report say?

In its 54-page investigative report released on Thursday, the National Police Agency concluded that the protection plan for Abe had neglected potential danger coming from behind him.

The report said security had been focused on risks to Abe during his movement from the site of his speech to his vehicle.

It said there had been shortfalls in the command system and communication among several key police officials, as well as their attention in areas behind Abe at the campaign site.

This, the report's authors said, led to their lack of attention on the suspect's movement until it was too late.

The suspect was already 7 meters (7.6 yards) behind Abe when he took out his homemade double-barrel gun resembling a camera with a long lens.

It was then that he blasted his first shot that narrowly missed Abe. It is believed that bodyguards could have saved the former prime ministers — either by shielding him or pulling him from the line of fire in the 2.5 seconds between the first shot and the second fatal shot.

The report called for significant strengthening in both training and staffing of Japan's dignitary protection. It also urged the revising of police protection guidelines for the first time in about 30 years.

Abe's suspected killer is believed to have targeted him because he thought the former leader was linked to the Unification Church.