More than 20 percent of ruling Liberal Democratic Party lawmakers have underreported revenues in political funds documents, an internal survey showed Tuesday, amid a slush funds scandal rattling the LDP.

However, opposition lawmakers criticized the survey for being insufficient as it did not inquire how the unreported funds were used from 384 LDP members, including 10 candidates for the next general election.

LDP General Council chief Hiroshi Moriyama told reporters that the investigative team he heads is seeking to publish the results of its inquiries into 85 members who have compiled improper reports by the end of the week.

Yasukazu Hamada (L), Diet affairs chief of the Liberal Democratic Party, and his Constitutional Democratic Party of Japan counterpart Jun Azumi meet in the parliament building in Tokyo on Feb. 13, 2024. (Kyodo)

The team started the investigation earlier this month, questioning lawmakers of the LDP, led by Prime Minister Fumio Kishida, about the amount of political funds they received from their factions, some of which have opted to disband in response to the scandal.

The LDP has come under intense scrutiny amid allegations that three factions, such as the one led by Kishida until December, neglected to report portions of their incomes from fundraising parties and established slush funds for distribution among their members.

According to the LDP survey, some lawmakers said their factions had instructed offices of their members not to report slush funds in political funds documents.

A total of 10 individuals belonging to the three groups have been either indicted or issued summary indictments by prosecutors. But executives of the factions have not faced criminal charges due to a lack of evidence implicating them.

In January, the LDP laid out internal reform proposals to strengthen its governance, which pledged to move away from factions as vehicles for securing funds and allocating important government and party posts for lawmakers.

On Tuesday, meanwhile, four opposition parties urged the LDP to hold a House of Representatives committee meeting on political ethics to compel senior members of the ruling party's largest faction and other groups to explain their involvement with slush funds.

The opposition parties also asked for lower house lawmaker Yoshitaka Ikeda, who has been indicted over the funds allegations for reportedly obtaining a significantly larger amount of slush funds than others, to be summoned to parliament to testify under oath.

Ikeda was a member of the biggest faction, previously headed by the late Prime Minister Shinzo Abe, before being expelled from the LDP in early January.

Former Chief Cabinet Secretary Hirokazu Matsuno, who had served as the Abe faction's secretary general responsible for practical affairs for the group, said he would comply with the request by the opposition parties to attend the committee on political ethics.

Matsuno, who had stepped down as chief Cabinet secretary in December, admitted failing to report 10.51 million yen ($70,280) for five years from 2018. The majority of members of the Abe faction are believed to have received slush funds from the group.

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