There were "undeniable" flaws in security for former Japanese Prime Minister Shinzo Abe, the head of police in the area where the leader was assassinated has admitted.

Tomoaki Onizuka, head of the Nara prefectural police, told reporters that a full investigation will take place.

"I believe it is undeniable that there were problems with the guarding and safety measures for former prime minister Abe," he said.

Earlier this morning, a hearse carrying the body of the assassinated former prime minister arrived in Tokyo from the western Japanese city where he was shot at close range on the campaign trail.

The murder of Japan's best-known politician rattled the country and sent shockwaves around the world, particularly given the nation's low levels of violent crime and strict gun laws.

The vehicle enter Mr Abe's residence in the capital, while senior members of his ruling Liberal Democratic Party, dressed in black, lined up to pay their respects.

The man accused of yesterday's shooting is in custody, with police saying he had confessed to killing the former prime minister, motivated by a belief that Mr Abe was linked to an unspecified organisation.

Police were investigating the unemployed 41-year-old's background, including claims he had served in Japan's navy, and said he appeared to have used a handmade gun.

Mr Abe was delivering a speech in Nara ahead of tomorrow's upper house elections when he was shot. Campaigning resumed today, with politicians saying they were determined to show democracy would prevail.

"We absolutely must not tolerate violence during an election to suppress speech," Prime Minister Fumio Kishida told around 600 supporters in central Japan's Yamanashi region, according to the Yomiuri Shimbun newspaper.

Mourners offer flowers near the crime scene

The Yomiuri and other Japanese media at Mr Kishida's first campaign event since the assassination described a tense mood and high levels of security, with a metal fence put up to separate the leader from the crowd.

Doctors said Mr Abe showed no vital signs when he arrived and died of enormous blood loss, despite massive transfusions.

They described multiple wounds to the politician's neck, with the internal damage reaching as deep as his heart.

Mr Abe's murder shook Japan, with Mr Kishida describing the killing as a "barbaric act" that was "unforgivable".

Mr Kishida was visibly emotional after the former leader's death was confirmed, saying he was "lost for words", and is expected to visit Mr Abe's Tokyo residence later today to pay his respects.

'Unacceptable act'

International reaction was similarly stark, with US President Joe Biden saying he was "stunned, outraged and deeply saddened", and ordering flags on US government buildings to fly at half-mast.

Australia announced that the Sydney Opera House would be lit up on Sunday in tribute to Abe.

Even regional powers with whom Mr Abe had clashed with have expressed condolences.

Mourners stand in line to pay tribute

South Korea's president called the killing an "unacceptable act", and the Chinese embassy in Japan praised Mr Abe's "contribution to the improvement and development" of ties.

Investigators are still piecing together a picture of the man behind the assassination and his motives.

He has been identified as Tetsuya Yamagami, and police said yesterday that he admitted to targeting Mr Abe over a grudge against an organisation he believed the former leader was linked to.

They have declined to name the organisation, though Japanese media outlets described it as a religious group.

Read more: Abe sought to reinvigorate Japan with bold policies

The gun he used "is clearly handmade in appearance", investigators said, and several other apparently handmade weapons were uncovered by police in protective gear who raided Mr Yamagami's home.

The suspect, who has been arrested on suspicion of murder, opened fire on Mr Abe shortly before noon yesterday.

Footage from public broadcaster NHK showed Mr Yamagami, dressed in a grey shirt and brown trousers, approaching from behind before drawing a weapon from a bag.

At least two shots appeared to be fired, each producing a cloud of smoke. As spectators and reporters ducked, he was tackled to the ground by security.

Funeral plans

Japanese media reported that a wake would be held Monday evening and a funeral on Tuesday for Mr Abe's close family and associates.

A hearse transporting the body of Shinzo Abe arrives at his residence

Both last night and this morning, a steady stream of mourners came to lay flowers and pray for Mr Abe, who had been Japan's longest-serving prime minister.

"I just couldn't sit back and do nothing. I had to come," said Nara resident Sachie Nagafuji, 54, visiting the scene with his son.

Mr Abe was the scion of a political family and became the country's youngest post-war prime minister when he took power for the first time in 2006, aged 52.

His turbulent first term ended in resignation for health reasons, but he returned to power in 2012 and stayed in office until the return of his ulcerative colitis forced a second resignation in 2020.

His hawkish, nationalist views were divisive, particularly his desire to reform the country's pacifist constitution to recognise the country's military, and he weathered a series of scandals, including allegations of cronyism.

However, he was lauded by others for his economic strategy, dubbed "Abenomics" and his efforts to put Japan firmly on the world stage, including by cultivating close ties with US president Donald Trump.

Higgins and Martin pay tribute to Abe

President Michael D Higgins

President Michael D Higgins has expressed his "deep condolences" to the Emperor of Japan at the "appalling" murder of former prime minister Shinzo Abe.

"The fact that he fell victim to this most brutal of crimes whilst actively engaging in Japan's democratic process of political choice makes today's events all the more appalling," he wrote in a letter to Tokyo's Imperial Palace.

In a letter to Emperor Naruhito, President Higgins paid tribute to Mr Abe, who was Japan's longest-serving prime minister.

"In this moment of darkness, we all take comfort in reflecting upon Mr Abe's distinguished career in public service in Japan, which spans the period both before and after your ascension to the Chrysanthemum Throne.

"Please know also, your Majesty, that Ireland and the Irish people share your sorrow and offer solidarity with you and the citizens of Japan, whom we count among our most long-standing friends and like-minded partners."

Taoiseach Micheál Martin also said he was "deeply saddened" by the "appalling" killing.

"He was a strong and committed democrat, and it is especially shocking that he was murdered while engaged in that most democratic of activities, campaigning ahead of an election," the Taoiseach said in a statement.

"Putting your arguments before an electorate and asking for their vote is at the very heart of what we believe in as democratic politicians. The attack on former PM Abe is therefore an attack on democracy itself.

"It is all the more shocking that it happened in a peace-loving country like Japan.

"My most heartfelt and sincere sympathies are with the people of Japan, whom PM Abe served with such commitment and distinction; with Prime Minister Kishida and his colleagues across Government; and especially with Mr Abe's family.

"On this very sad occasion, on behalf of the Government and people of Ireland, I extend our most profound condolences and solidarity."