Prosecutors allege Liberal Democratic Party factions failed to report fundraising proceeds.

Investigators from the Tokyo District Public Prosecutors’ Office searched the offices of two LPD factions associated with former Prime Minister Shinzo Abe and former secretary-general Toshihiro Nikai, local media reported on Tuesday.

Prosecutors are investigating allegations that party officials failed to declare a combined 600 million yen ($4.18m) in fundraising proceeds, directing money to faction-run slush funds.

LDP secretary-general Toshimitsu Motegi said the raids were “extremely regrettable” and the party would take “necessary measures while observing the fate of the investigation”.

The scandal has fuelled public discontent with the LPD and Kishida, who last week sacked four cabinet members implicated in the allegations, including Chief Cabinet Secretary Hirokazu Matsuno, in an effort to stem the fallout.

“The party must work to restore the trust of the people with a strong sense of urgency,” Kishida told reporters on Tuesday.

“I’ll double down my efforts as the leader of the LDP to restore trust,” Kishida told a news conference last week.

Kishida’s cabinet reshuffle, however, has done little to boost his flagging approval.

In an opinion poll published by the Mainichi newspaper on Sunday, 79 of respondents said they disapproved of the government – the highest figure since the poll began in 1947.

Other polls by the Asahi, Yomiuri and Nikkei newspapers over the weekend put Kishida’s approval rating at about 20 percent, the lowest of any premier since the LDP returned to power in 2012 following a brief interruption in its decades-long ruling streak.

Kishida, who has already reshuffled his cabinet twice, does not need to hold an election until October 2025, and Japan’s weak opposition parties have historically struggled to compete with the LDP.