Japan's opposition lawmakers are heaping pressure on Prime Minister Kishida Fumio over a political money scandal.

Several factions of the main ruling Liberal Democratic Party are accused of paying kickbacks to lawmakers who exceeded their quotas for sales of tickets to fundraiser events.

The factions also allegedly failed to disclose the payouts in their financial reports.

Members of the opposition grilled Kishida in the Diet on Friday as three senior LDP officials were named in the scandal, including the government's top spokesperson.

Sources say the office of Chief Cabinet Secretary Matsuno Hirokazu may have received unreported payouts of nearly 70,000 dollars from the LDP's largest faction over five years.

Opposition lawmakers pressed Matsuno for an explanation. They also took shots at Kishida.

Constitutional Democratic Party's Renho said, "This is a slush fund scandal. The chief cabinet secretary himself is said to be the recipient of the money. You should dismiss him."

Kishida said, "It's not inappropriate for me to refrain from speaking out of concern that it could affect the investigation."

The offices of two other key figures in the faction are also accused of receiving kickbacks. They include Takagi Tsuyoshi, who succeeded Matsuno as the group's secretary general, and senior Upper House official Seko Hiroshige. Both have served as cabinet ministers.

Members of political organizations who are found guilty of failing to report revenue from fundraising events could face fines or imprisonment. They can also be suspended from voting and running for election.

Prosecutors are reportedly considering whether to summon lawmakers for voluntary questioning.

Opposition members say they're discussing the possibility of a no-confidence vote against the Cabinet.