Escalating scandal involving allegations of unreported kickbacks from ruling party fundraising claims key ministers.

Matsuno, whose official title is Chief Cabinet Secretary, announced his resignation on Thursday after Economy and Industry Minister Yasutoshi Nishimura also quit.

Jiji Press and other Japanese media said Internal Affairs Minister Junji Suzuki and Agriculture Minister Ichiro Miyashita were also stepping down and that five deputy ministers would be let go.

The ministers all come from the so-called Abe faction, which is named after the assassinated former Prime Minister Shinzo Abe and is the biggest and most powerful faction in the ruling Liberal Democratic Party (LDP).

Japanese prosecutors have begun a criminal investigation into the faction over allegations of receiving about 500 million yen ($3.5m) in fundraising proceeds missing from party accounts, news outlets reported.

“In light of the various allegations made regarding political funds, which have shaken the public trust in politics, and the various allegations made regarding my own political funds, I have submitted my resignation,” Matsuno said at a press conference. He will be replaced by Yoshimasa Hayashi, who was the foreign minister until September.

Kishida announced late on Wednesday that he would revamp his government as he battles to control the fallout from the scandal in the party, which has led Japan almost uninterrupted since the end of World War II.

He said he regretted that the scandal had deepened political distrust and insisted he would take urgent steps to tackle it.

“We will tackle the various issues surrounding political funds head-on… I will make efforts like a ball of fire and lead the LDP to restore the public’s trust,” he told reporters.

Investigators are expected to start searching lawmakers’ offices for evidence as early as next week, according to broadcaster NTV, and to examine whether other LDP factions – including one led by Kishida until last week – are involved, according to the reports.

Nishimura was quoted as telling reporters on Thursday: “The public’s doubts are around me over political funds, which is leading to distrust in the government. As an investigation is going on, I thought I wanted to set things right.”

Since news of the latest scandal broke a few weeks ago, Kishida has seen his public support drop to about 23 percent, the lowest since he came into office in October 2021, according to a recent poll by national broadcaster NHK.

Support for the LDP has also slumped.

The prime minister, who has already reshuffled his cabinet twice, does not need to hold an election until October 2025, and a fractured and weak opposition has historically struggled to make sustained inroads against the LDP.

Opposition groups led by the Constitutional Democratic Party (CDPJ) of Japan led an unsuccessful no-confidence motion against Kishida on Wednesday.

“The LDP has no self-cleansing ability,” CDPJ leader Kenta Izumi said. “It is questionable if they can choose anyone who is not involved in slush funds.”

Japanese Communist Party leader Kazuo Shii called the scandal “a bottomless, serious problem”.

Matsuno allegedly diverted more than 10 million yen ($70,600) over the past five years from money he raised from faction fundraising events to a slush fund, while Nishimura allegedly kept 1 million yen ($7,000), according to media reports.

While most senior figures mentioned in the media remained mum, Vice Defence Minister Hiroyuki Miyazawa said on Wednesday that he was told by the Abe faction that “it’s OK to not enter” his first kickbacks in 2020-2022 in the funds’ records and that he assumed it was a practice that had been going on for years and was legal.

Miyazawa also said that while he had been ordered to keep quiet, he felt compelled to speak out. The amount he accepted was reportedly just 1.4 million yen ($9,800).

Collecting proceeds from party events and paying kickbacks to lawmakers are not illegal in Japan if recorded appropriately under the political funds law. Not reporting such payments carries a penalty of as many as five years in prison but prosecution is difficult because it needs proof of a specific instruction to an accountant to not report the transfer.