Japanese Prime Minister Fumio Kishida reiterated Thursday that holding a state funeral for former leader Shinzo Abe is "appropriate," given his achievements as the country's longest-serving premier.

With opposition to the slain former leader's state funeral mounting, Kishida appeared in a parliamentary session to debate the Sept. 27 event for Abe, who was fatally shot by a lone gunman during an election campaign speech in early July.

To offer condolences across the nation, the government "needs" to hold the funeral as a "state event," Kishida said.

At a regular press conference earlier in the day, Chief Cabinet Secretary Hirokazu Matsuno said the government had decided to hold the state funeral to express appreciation for Abe, taking into consideration the condolence messages received from other countries.

"We have judged it appropriate to hold it as an official event and welcome representatives from abroad," the top government spokesman said.

Matsuno added that U.S. Vice President Kamala Harris, European Council President Charles Michel and Australian Prime Minister Anthony Albanese are among the foreign dignitaries expected to travel to Japan for the state funeral.

Kishida's decision to hold the state funeral has been questioned, with Abe's divisive political stances and a series of scandals linked to him cited in addition to the massive amount of taxpayers' money to be used for the event.

Prime Minister Fumio Kishida (C) speaks in a parliamentary session in the Diet on Sept. 8, 2022. (Kyodo)

Some opposition parties have criticized Abe's nationalistic views on history and security, with the Japanese Communist Party saying it will boycott the state funeral that it claims is unconstitutional.

The government estimates the costs for preparing the venues, security and welcoming foreign guests at more than 1.6 billion yen ($11 million).

With calls growing for Kishida to explain the reasoning for holding a state funeral, the prime minister has decided to attend the Diet sessions.

During the sessions, Kishida is also expected to touch on ties between members of his ruling Liberal Democratic Party and a controversial religious group that has come under the spotlight since Abe's shooting.

Kishida has urged his party lawmakers to sever relations with the Unification Church, notorious for its "spiritual sales" in which people are coerced into buying jars and other items for exorbitant prices.

Abe was targeted due to his perceived links to the church, now officially called the Family Federation for World Peace and Unification. The assailant has told investigators that his mother's substantial donations to the group ruined his family's finances.

Kishida has called for all-out efforts to investigate ties between LDP lawmakers and the Unification Church, founded by a staunch anti-communist and known for its mass weddings.

The ruling party is expected to publish the results of the investigation later in the day.

After Kishida reshuffled his Cabinet and party executive lineups in August, it was revealed that many of those involved had some ties to the Unification Church.

The revelations added to the evidence of a densely intertwined network of contacts between LDP lawmakers and the Unification Church, established in South Korea in 1954 by the late Sun Myung Moon and labeled a cult by critics.

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